# David Yarkony

## D. Mead Johnson Professor of Chemistry

### Contact Information

- [email protected]
- Curriculum Vitae
- Remsen 310
- 410-516-4663
- Group/Lab Website

**Research Interests: **Theoretical chemical physics

**Education: **PhD, University of California, Berkeley

David R. Yarkony was born in New York City. He graduated from State University of New York at Stony Brook, with a Bachelor of Arts in chemistry, summa cum laude, in 1971. He received his Ph. D. in chemistry from the University of California at Berkeley in 1975, with H. F. Schaefer III and after two years at the Massachusetts Institute of Technology working with Robert J. Silbey on temperature effects on excitons and exciton transport, he joined the faculty at Johns Hopkins University in 1977. He was promoted to full professor in 1984 and is currently the D. Mead Johnson Professor of Chemistry.

Professor Yarkony has been interested in nonadiabatic chemistry since 1985 when he, in collaboration with Byron Lengsfield and Paul Saxe, reported to a unique algorithm for determining the first derivative or momentum coupling for multireference configuration interactions wave function using analytic gradient techniques. This lead Yarkony, in the 1990's to develop algorithms to locate and characterize conical intersections of states of the same symmetry. These algorithms have shaped his career as he and several other groups have demonstrated that such conical intersections are ubiquitous and must be considered in any ultrafast nonadiabatic process.

More recently Yarkony has turned his attention to the effects of conical intersections on photoelectron spectra and photodissociation. Here a key issue is the accuracy of the adiabatic electronic structure data, energies, energy gradients and derivative couplings, used in the simulations. Yarkony, with Michael Schuurman (bound molecules) and Xiaolei Zhu (dissociative species) have developed algorithms to construct accurate quasi-diabatic representation of high level electronic structure data. These algorithms are having a major impact on the accuracy with which nonadiabatic processes can be simulated.

We are interested in electronically nonadiabatic processes, processes in which the Born-Oppenheimer approximation fails and a molecular wave function can transition radiationlessly between potential energy surfaces. Although the Born-Oppenheimer approximation is fundamental to the way we think about and quantify virtually all of chemistry, its breakdown, rather than being a rare event is quite common, when an electronically excited state is involved. Since electronically excited states are routinely formed when visible and higher energy photons are absorbed nonadiabatic processes are of fundamental importance in such diverse areas as vision, photosynthesis, solar energy conversion, photochemistry and the photo stability of biomolecules.

The Born-Oppenheimer approximation fails in dramatic fashion in the vicinity of conical intersections, which represent the intersection of two (or more) Born-Oppenheimer potential energy surfaces with the topography of a double cone. Once thought of as an archane theoretical notion largely restricted to molecules with point group symmetry, as for example in the Jahn-Teller effect, due to work reported in the past two decades conical intersections that do not involve point group symmetry are now understood to be ubiquitous. Over that period we have developed a computationally oriented, formal description of conical intersections, including extensions to intersections of 3-states and intersections where the spin-orbit interaction cannot be neglected.

### Selected publications

Matsunaga, Nikita and Yarkony, David R. Energies and derivative couplings in the vicinity of a conical intersection. 3. The ‘most’ diabatic basis. Molecular Physics. 1998, 93(1), 79-84.

Matsika, Spiridoula and Yarkony, David R. Accidental conical intersections of three states of the same symmetry. I. Location and relevance. Journal of Chemical Physics. 2002, 117(15), 6907-10.

Matsika, Spiridoula and Yarkony, David R. Spin-Orbit Coupling and Conical Intersections. IV. A Perturbative Determination of the Electronic Energies, Derivative Couplings, and a Rigorous Diabatic Representation near a Conical Intersection. The General Case. Journal of Physical Chemistry B. 2002, 106(33), 8108-16.

**Some relevant review articles include:**

Yarkony, David R. Diabolical conical intersections. Reviews of Modern Physics. 1996, 68(4), 985-1013.

Yarkony, David R. Conical Intersections: Diabolical and Often Misunderstood. Accounts of Chemical Research. 1998, 31(8), 511-8.

Our current research objectives focus on how nonadiabatic interactions induced by conical intersections are reflected in dynamical process and measured spectra. Another major area of interest is the electronic structure and dynamical aspects of nonadiabatic photodissociation mediated by conical intersections. We have considerable expertise in the electronic structure aspects of this problem. We have extended our method for determining quasi-diabatic coupled electronic state Hamiltonians for bound molecules to handle dissociating systems.

Zhu, Xiaolei and Yarkony, David R. Toward eliminating the electronic structure bottleneck in nonadiabatic dynamics on the fly: An algorithm to fit nonlocal, quasidiabatic, coupled electronic state Hamiltonians based on ab initio electronic structure data. Journal of Chemical Physics. 2010, 132(10), 104101.

Zhu, Xiaolei and Yarkony, David R. On the Representation of Coupled Adiabatic Potential Energy Surfaces using Quasi-Diabatic Hamiltonians: Description of Accidental Seams of Conical Intersection. Molec. Phys. 2010, 108(19-20), 2611-19.

We are preparing for publication full 6-dimensional coupled potential energy surfaces for the 1,21A states of NH3. One of the major goals for our research is to extend the range of molecules accessible to this approach and use it to construct highly efficient dynamics on the fly methodologies.

One of the uses of the methodological tools being developed in our group is the calculation of photodetachment spectra. In these calculations ab initio determination of the electron photodetachment cross sections, basically the transition moments to the individual diabatic electronic states for the continuum electron, is important. Despite its importance, this aspect of the problem, a challenging exercise in nonadiabatic electron scattering theory, has received little attention. We have developed a unique, fully nonadiabatic formalism to treat this electron scattering problem, which builds on our above described spectral simulation tools, takes full account of the nuclear kinetic energy, and exact account of electron exchange.

### Edited Books

- The Jahn-Teller Effect. Fundamentals and Implications for Physics and Chemistry editors, Horst Köppel, Heinz Barentzen, David R. Yarkony, (Springer, 2009)
- Conical Intersections: Electronic Structure, Dynamics and Spectroscopy, editors Wolfgang Domcke, David R. Yarkony and Horst Köppel, World Scientific Publishing, (Singapore, 2004)
- Modern Electronic Structure Theory Part 1, David R. Yarkony. World Scientific Publishing, London. (1995).
- Modern Electronic Structure Theory Part 2, David R. Yarkony. World Scientific Publishing, London. (1995).

### Invited Publications

- A Continuous Representation of the Branching Spaces of Two State Conical Intersections Along their Seams. A Group Homomorphism Approach. Seungsuk Han and David R. Yarkony, in Conical Intersections, G, Worth and S. Althorpe, eds. (CCP6, , 2005)
- Determination of potential energy surface intersections and derivative couplings in the adiabatic representation David. R. Yarkony, in Conical Intersections: Electronic Structure, Dynamics and Spectroscopy, Wolfgang Domcke, David R. Yarkony and Horst Köppel, eds. World Scientific Publishing, Singapore, (2004), pp.129-174.
- Conical Intersections: Their description and consequences, David. R. Yarkony, in Conical Intersections: Electronic Structure,Dynamics and Spectroscopy, Wolfgang Domcke, David R. Yarkony and Horst Köppel, eds. World Scientific Publishing, Singapore, (2004), pp 41-128.
- Conical Intersections and the Spin-Orbit Interaction, Spiridoula Matsika and David R. Yarkony, in The Role of Degenerate States in Chemistry, Advances in Chemical Physics, Michael Baer and Gert. D. Billing, eds, J. Wiley, New York, 2002, pp. 557-583
- Conical intersections: The New Conventional Wisdom – Feature Article, D. R. Yarkony, J. Phys. Chem. A 105, 6277-6293 (2001).
- Perspective on:Some Recent Developments in the Theory of Molecular Energy Levels: by H. C. Longuet-Higgins[Advances in Spectroscopy 2, 429-472 (1961)]. The geometric phase effect. David R. Yarkony, Theoretical Chemistry Accts, New century issue, 103, 242-246 (2000).
- Vibronic Energies and the breakdown of the Born-Oppenheimer approximation in diatomic molecules: Adiabatic and Diabatic representations. David R. Yarkony, in Computational Molecular Spectroscopy; Jensen, P. ;Bunker, P., Eds.; J. Wiley, Chichester, 2000; p. 459-484.
- Conical Intersection Diabolical and Often Misunderstood, solicited article. David R. Yarkony, Accounts of Chemical Research, 31, 511-518 (1998).
- Nonadiabatic Derivative Couplings David R. Yarkony, in Encyclopedia of Computational Chemistry, editor-in-chief P. von Ragué Schleyer (John-Wiley, 1998).
- Current Issues in Nonadiabatic Chemistry – Feature Article, D. R.. Yarkony J. Phys. Chem. 100, 18612-18628 (1996)
- Diabolical Conical Intersections D. R. Yarkony, Rev. Mod. Phys. 68, 985-1013 (1996).
- Molecular structure D. R. Yarkony, in Atomic, Molecular and Optical Physics Handbook, G. F. Drake, editor (AIP, 1996).

### Journal Articles

- Nonadiabatic Tunneling in Photodissociation of Phenol. Xie C, Ma J, Zhu X, Yarkony DR, Xie D, Guo H. J Am Chem Soc. 2016 Jun 29;138(25):7828-31.
- An improved quasi-diabatic representation of the 1, 2, 3(1)A coupled adiabatic potential energy surfaces of phenol in the full 33 internal coordinates. Zhu X, Malbon CL, Yarkony DR. J Chem Phys. 2016 Mar 28;144(12):124312.
- Constructing diabatic representations using adiabatic and approximate diabatic data–Coping with diabolical singularities. Zhu X, Yarkony DR. J Chem Phys. 2016 Jan 28;144(4):044104.
- On the elimination of the electronic structure bottleneck in on the fly nonadiabatic dynamics for small to moderate sized (10-15 atom) molecules using fit diabatic representations based solely on ab initio electronic structure data: The photodissociation of phenol. Zhu X, Yarkony DR. J Chem Phys. 2016 Jan 14;144(2):024105.
- On the Construction of Property Based Diabatizations: Diabolical Singular Points. Zhu X, Yarkony DR. J Phys Chem A. 2015 Dec 17;119(50):12383-91. doi: 10.1021/acs.jpca.5b07705.
- Nonadiabatic Photodissociation of the Hydroxymethyl Radical from the 2(2)A State. Surface Hopping Simulations Based on a Full Nine-Dimensional Representation of the 1,2,3(2)A Potential Energy Surfaces Coupled by Conical Intersections. Malbon CL, Yarkony DR. J Phys Chem A. 2015 Jul 16;119(28):7498-509.
- Communication: On the competition between adiabatic and nonadiabatic dynamics in vibrationally mediated ammonia photodissociation in its A band. Xie C, Zhu X, Ma J, Yarkony DR, Xie D, Guo H. J Chem Phys. 2015 Mar 7;142(9):091101.
- On the description of conical intersections–a continuous representation of the local topography of seams of conical intersection of three or more electronic states: a generalization of the two state result. Zhu X, Yarkony DR. J Chem Phys. 2014 Nov 7;141(17):174109.
- Full-dimensional quantum dynamics of vibrationally mediated photodissociation of NH3 and ND3 on coupled ab initio potential energy surfaces: absorption spectra and NH2(Ã(2)A1)/NH2(X̃(2)B1) branching ratios. Ma J, Xie C, Zhu X, Yarkony DR, Xie D, Guo H. J Phys Chem A. 2014 Dec 26;118(51):11926-34.
- Full-Dimensional Quantum State-to-State Nonadiabatic Dynamics for Photodissociation of Ammonia in its A-Band. Xie C, Ma J, Zhu X, Zhang DH, Yarkony DR, Xie D, Guo H. J Phys Chem Lett. 2014 Apr 3;5(7):1055-60.
- Fitting coupled potential energy surfaces for large systems: method and construction of a 3-state representation for phenol photodissociation in the full 33 internal degrees of freedom using multireference configuration interaction determined data. Zhu X, Yarkony DR. J Chem Phys. 2014 Jan 14;140(2):024112.
- On the photoionization spectrum of propyne: a fully ab initio simulation of the low-energy spectrum including the Jahn-Teller effect and the spin-orbit interaction. Marquez S, Dillon J, Yarkony DR. J Phys Chem A. 2013 Nov 21;117(46):12002-10.
- On the mechanism for the nonadiabatic reactive quenching of OH(A2Σ+) by H2(1Σg+): the role of the 2(2)A state. Dillon J, Yarkony DR. J Chem Phys. 2013 Aug 14;139(6):064314.
- On the electronic structure of the low lying electronic states of vanadium trioxide. Lee EM, Zhu X, Yarkony DR. J Chem Phys. 2013 Jul 28;139(4):044303.
- Seams of conical intersections relevant to the quenching of OH(A(2)Σ(+)) by collisions with H2. Dillon J, Yarkony DR. J Phys Chem A. 2013 Aug 15;117(32):7344-55.
- First principles determination of the NH2∕ND2(Ã,X̃) branching ratios for photodissociation of NH3∕ND3 via full-dimensional quantum dynamics based on a new quasi-diabatic representation of coupled ab initio potential energy surfaces. Ma J, Zhu X, Guo H, Yarkony DR. J Chem Phys. 2012 Dec 14;137(22):22A541.
- Quasi-diabatic representations of adiabatic potential energy surfaces coupled by conical intersections including bond breaking: a more general construction procedure and an analysis of the diabatic representation. Zhu X, Yarkony DR. J Chem Phys. 2012 Dec 14;137(22):22A511.
- Nonadiabatic effects in substitutional isomers of Jahn-Teller molecules: the strange case of hydroxymethoxy. Dillon J, Yarkony DR. J Chem Phys. 2012 Oct 21;137(15):154315.
- Reactive quenching of OH A 2Σ+ by O2 and CO: experimental and nonadiabatic theoretical studies of H- and O-atom product channels. Lehman JH, Lester MI, Yarkony DR. J Chem Phys. 2012 Sep 7;137(9):094312.
- Computational determination of the Ã state absorption spectrum of NH3 and of ND3 using a new quasi-diabatic representation of the X and Ã states and full six-dimensional quantum dynamics. Zhu X, Ma J, Yarkony DR, Guo H. J Chem Phys. 2012 Jun 21;136(23):234301.
- On the representation of coupled adiabatic potential energy surfaces using quasi-diabatic Hamiltonians: a distributed origins expansion approach. Zhu X, Yarkony DR. J Chem Phys. 2012 May 7;136(17):174110.
- Role of conical intersections in molecular spectroscopy and photoinduced chemical dynamics. Domcke W, Yarkony DR. Annu Rev Phys Chem. 2012;63:325-52.
- Nonadiabatic quantum chemistry–past, present, and future. Yarkony DR. Chem Rev. 2012 Jan 11;112(1):481-98.
- On the simulation of photoelectron spectra complicated by conical intersections: higher-order effects and hot bands in the photoelectron spectrum of triazolide (CH)2N3(-). Dillon J, Yarkony DR, Schuurman MS. J Chem Phys. 2011 May 14;134(18):184314.
- Determining partial differential cross sections for low-energy electron photodetachment involving conical intersections using the solution of a Lippmann-Schwinger equation constructed with standard electronic structure techniques. Han S, Yarkony DR. J Chem Phys. 2011 May 7;134(17):174104.
- On the determination of partial differential cross sections for photodetachment and photoionization processes producing polyatomic molecules with electronic states coupled by conical intersections. Han S, Yarkony DR. J Chem Phys. 2011 Apr 7;134(13):134110.
- On the construction of quasidiabatic state representations of bound adiabatic state potential energy surfaces coupled by accidental conical intersections: incorporation of higher order terms. Dillon J, Yarkony DR, Schuurman MS. J Chem Phys. 2011 Jan 28;134(4):044101.
- Seungsuk Han and David R. Yarkony. On the determination of intensities for electron photodetachment and photoionization spectra involving states coupled by conical intersections: Total integral cross sections for polyatomic molecules. Journal of Chemical Physics. 2010, 133(19), 194107
- Zhu, Xiaolei and Yarkony, David R. On the representation of coupled adiabatic potential energy surfaces using quasi-diabatic Hamiltonians: description of accidental seams of conical intersection. Molecular Physics. 2010, 108(19-20), 2611-2619
- Samanta, Kousik; Yarkony, David R. On the Role of Conical Intersections and their Local Topography in the Photodissociation of 1-Hydroxyethyl Radical. Journal of Chemical Physics. 2010,
- Zhu, Xiaolei and Yarkony, David R. Toward eliminating the electronic structure bottleneck in nonadiabatic dynamics on the fly: An algorithm to fit nonlocal, quasidiabatic, coupled electronic state Hamiltonians based on ab initio electronic structure data. Journal of Chemical Physics. 2010, 132(10), 104101/1,104101/15.
- Zhu, Xiaolei and Yarkony, David R. The Photoelectron Spectrum of Pyrrolide: Nonadiabatic Effects due to Conical Intersections. Journal of Physical Chemistry C. 2010, 114(12), 5312-20.
- Dillon, Joseph J. and Yarkony, David R. The photoelectron spectrum of the ethoxide anion: conical intersections, the spin-orbit interaction, and sequence bands. Journal of Chemical Physics. 2009, 131(13), 134303.
- Zhu, Xiaolei and Yarkony, David R. On the determination of optimized, fully quadratic, coupled state quasidiabatic Hamiltonians for determining bound state vibronic spectra. Journal of Chemical Physics. 2009, 130(23), 234108.
- Dillon, Joseph J. and Yarkony, David R. The photoelectron spectrum of the isopropoxide anion: nonadiabatic effects due to conical intersections and the spin-orbit interaction. Journal of Chemical Physics. 2009, 130(15), 154312.
- Papas, Brian N.; Schuurman, Michael S.; Yarkony, David R. The simulated photoelectron spectrum of 1-propynide. Journal of Chemical Physics. 2009, 130(6), 064306.
- Schuurman, Michael S.; Young, Richard A.; Yarkony, David R. On the multimode quadratic vibronic coupling problem: An open-ended solution using a parallel Lanczos algorithm. Chemical Physics. 2008, 347(1-3), 57-64.
- Papas, Brian N.; Schuurman, Michael S.; Yarkony, David R. Determining quasidiabatic coupled electronic state Hamiltonians using derivative couplings: A normal equations based method. Journal of Chemical Physics. 2008, 129(12), 124104.
- Schuurman, Michael S. and Yarkony, David R. A simulation of the photoelectron spectrum of pyrazolide. Journal of Chemical Physics. 2008, 129(6), 064304.
- Schuurman, Michael S. and Yarkony, David R. A method to reduce the size of the vibronic basis employed in the simulation of spectra using the multimode vibronic coupling approximation. Journal of Chemical Physics. 2008, 128(4), 044119.
- Schuurman, Michael S.; Weinberg, Daniel E.; Yarkony, David R. On the simulation of photoelectron spectra in molecules with conical intersections and spin-orbit coupling: the vibronic spectrum of CH3S. Journal of Chemical Physics. 2007, 127(10), 104309.
- Schuurman, Michael S. and Yarkony, David R. On the vibronic coupling approximation: a generally applicable approach for determining fully quadratic quasidiabatic coupled electronic state Hamiltonians. Journal of Chemical Physics. 2007, 127(9), 094104.
- Dillon, Joseph J. and Yarkony, David R. Seams near seams: the Jahn-Teller effect in the 1E” state of N3+. Journal of Chemical Physics. 2007, 126(12), 124113.
- Schuurman, Michael S. and Yarkony, David R. On the locus of points of conical intersection: seams near seams. Journal of Chemical Physics. 2007, 126(4), 044104.
- Young, R. A.,Jr and Yarkony, David R. Towards a highly efficient theoretical treatment of Jahn-Teller effects in molecular spectra: the 1 2A and 2 2A electronic states of the ethoxy radical. Journal of Chemical Physics. 2006, 125(23), 234301.
- Schuurman, Michael S. and Yarkony, David R. On the characterization of three state conical intersections using a group homomorphism approach: mapping the full N-5 dimensional seam space. Journal of Chemical Physics. 2006, 124(24), 244103.
- Schuurman, Michael S. and Yarkony, David R. On the characterization of three state conical intersections: A quasianalytic theory using a group homomorphism approach. Journal of Chemical Physics. 2006, 124(12), 124109.
- Schuurman, Michael S. and Yarkony, David R. On the Characterization of Three-State Conical Intersections Using a Group Homomorphism Approach: The Two-State Degeneracy Spaces. Journal of Physical Chemistry B. 2006, 110(38), 19031-9.
- Yarkony, David R. On the connectivity of seams of conical intersection: seam curvature. Journal of Chemical Physics. 2005, 123(20), 204101.
- Yarkony, David R. Escape from the double cone: optimized descriptions of the seam space using gateway modes. Journal of Chemical Physics. 2005, 123(13), 134106.
- Young, R. A. and Yarkony, David R. A novel conical intersection topography and its consequences: the 1, 2 2A conical intersection seam of the vinoxy radical. Journal of Chemical Physics. 2005, 123(8), 084315.
- Yarkony, David R. Statistical and nonstatistical nonadiabatic photodissociation from the first excited state of the hydroxymethyl radical. Journal of Chemical Physics. 2005, 122(8), 84316.
- Yarkony, David R. Marching along ridges. An extrapolatable approach to locating conical intersections. Faraday Discussions. 2004, 127, 325-36.
- Yarkony, David R. Exploring molecular complexity: Conical intersections and NH3 photodissociation. Journal of Chemical Physics. 2004, 121(2), 628-31.
- Dallos, Michal; Lischka, Hans; Shepard, Ron; Yarkony, David R.; Szalay, Peter G. Analytic evaluation of nonadiabatic coupling terms at the MR-CI level. II. Minima on the crossing seam: Formaldehyde and the photodimerization of ethylene. Journal of Chemical Physics. 2004, 120(16), 7330-9.
- Lischka, Hans; Dallos, Michal; Szalay, Peter G.; Yarkony, David R.; Shepard, Ron. Analytic evaluation of nonadiabatic coupling terms at the MR-CI level. I. Formalism. Journal of Chemical Physics. 2004, 120(16), 7322-9.
- Dykstra, Clifford E.; Garrison, Barbara J.; Scuseria, Gustavo E.; Yarkony, David R. Dedication to Fritz Schaefer. Journal of Physical Chemistry A. 2004, 108(15), 2803-4.
- Dykstra, Clifford E.; Garrison, Barbara J.; Scuseria, Gustavo E.; Yarkony, David R. Biography of Fritz Schaefer. Journal of Physical Chemistry A. 2004, 108(15), 2805-7.
- Yarkony, David R. Marching along Ridges. Efficient Location of Energy-Minimized Conical Intersections of Two States Using Extrapolatable Functions. Journal of Physical Chemistry A. 2004, 108(15), 3200-5.
- Williams, Skip; Gupta, Manish; Owano, Thomas, et al. Quantitative detection of singlet O2 by cavity-enhanced absorption. Optics Letters. 2004, 29(10), 1066-8.
- Han, Seungsuk and Yarkony, David R. Conical intersections of three states: Energies, derivative couplings, and the geometric phase effect in the neighborhood of degeneracy subspaces. Application to the allyl radical. Journal of Chemical Physics. 2003, 119(22), 11561-9.
- Han, Seungsuk and Yarkony, David R. Nonadiabatic processes involving three electronic states. I. Branch cuts and linked pairs of conical intersections. Journal of Chemical Physics. 2003, 119(10), 5058-68.
- Han, Seungsuk and Yarkony, David R. On the properties of the seam and branching spaces of conical intersections in molecules with an odd number of electrons: A group homomorphism approach. Journal of Chemical Physics. 2003, 118(22), 9952-62.
- Matsika, Spiridoula and Yarkony, David R. Conical Intersections of Three Electronic States Affect the Ground State of Radical Species with Little or No Symmetry: Pyrazolyl. Journal of the American Chemical Society 2003, 125(41), 12428-9.
- Matsika, Spiridoula and Yarkony, David R. Beyond Two-State Conical Intersections. Three-State Conical Intersections in Low Symmetry Molecules: the Allyl Radical. Journal of the American Chemical Society 2003, 125(35), 10672-6.
- Matsika, Spiridoula and Yarkony, David R. Conical intersections and the spin-orbit interaction. Advances in Chemical Physics 2002, 124 (Role of Degenerate States in Chemistry), 557-81.
- Matsika, Spiridoula and Yarkony, David R. Photodissociation of the vinoxy radical through conical, and avoided, intersections. Journal of Chemical Physics. 2002, 117(15), 7198-206.
- Matsika, Spiridoula and Yarkony, David R. Accidental conical intersections of three states of the same symmetry. I. Location and relevance. Journal of Chemical Physics. 2002, 117(15), 6907-10.
- Matsika, Spiridoula and Yarkony, David R. Conical intersections and the nonadiabatic reactions H2O + O(3P )↔OH(A 2Σ +) + OH(X 2Π). Journal of Chemical Physics. 2002, 117(8), 3733-40.
- Hoffman, Brian C. and Yarkony, David R. Photodissociation of the hydroxymethyl radical. I. The role of conical intersections in line broadening and decomposition pathways. Journal of Chemical Physics. 2002, 116(19), 8300-6.
- Matsika, Spiridoula and Yarkony, David R. Spin-orbit coupling and conical intersections in molecules with an odd number of electrons. III. A perturbative determination of the electronic energies, derivative couplings and a rigorous diabatic representation near a conical intersection. Journal of Chemical Physics. 2002, 116(7), 2825-35.
- Matsika, Spiridoula and Yarkony, David R. Intersecting Conical Intersection Seams: Their Location, Representation, and Effect on Local Topography. Journal of Physical Chemistry A. 2002, 106(11), 2580-91.
- Matsika, Spiridoula and Yarkony, David R. Spin-Orbit Coupling and Conical Intersections. IV. A Perturbative Determination of the Electronic Energies, Derivative Couplings, and a Rigorous Diabatic Representation near a Conical Intersection. The General Case. Journal of Physical Chemistry B. 2002, 106(33), 8108-16.
- Matsika, Spiridoula and Yarkony, David R. On the effects of spin-orbit coupling on conical intersection seams in molecules with an odd number of electrons. II. Characterizing the local topography of the seam. Journal of Chemical Physics. 2001, 115(11), 5066-75.
- Abrol, Ravinder; Shaw, Amy; Kuppermann, Aron; Yarkony, David R. Accurate first-derivative nonadiabatic couplings for the H3 system. Journal of Chemical Physics. 2001, 115(10), 4640-59.
- Matsika, Spiridoula and Yarkony, David R. On the effects of spin-orbit coupling on conical intersection seams in molecules with an odd number of electrons. I. Locating the seam. Journal of Chemical Physics. 2001, 115(5), 2038-50.
- Yarkony, David R. Characterizing the local topography of conical intersections using orthogonality constrained parameters: Application to the internal conversion S1 -> S0 in HNCO. Journal of Chemical Physics. 2001, 114(6), 2614-22.
- Yarkony, David R. Nuclear dynamics near conical intersections in the adiabatic representation: I. The effects of local topography on interstate transitions. Journal of Chemical Physics. 2001, 114(6), 2601-13.
- Yarkony, David R. Conical Intersections: The New Conventional Wisdom. Journal of Physical Chemistry A. 2001, 105(26), 6277-93.
- Yarkony, David R. Symmetry Friend or Foe: Confluences of Conical Intersection Seams in Tetra-Atomic Molecules. Journal of Physical Chemistry A. 2001, 105(12), 2642-5.
- Yarkony, David R. Intersecting conical intersection seams in tetra-atomic molecules: the S1-S0 internal conversion in HNCO. Molecular Physics. 2001, 99(17), 1463-7.
- Kryachko, Eugene S. and Yarkony, David R. Diabatic bases and molecular properties. International Journal of Quantum Chemistry. 2000, 76(2), 235-43.
- Hoffman, Brian C. and Yarkony, David R. The role of conical intersections in the nonadiabatic quenching of OH (A2Σ+) by molecular hydrogen. Journal of Chemical Physics. 2000, 113(22), 10091-9.
- Yarkony, David R. On the adiabatic to diabatic states transformation near intersections of conical intersections. Journal of Chemical Physics. 2000, 112(5), 2111-20.
- Yarkony, David R. Perspective on “Some recent developments in the theory of molecular energy levels”. Theoretical Chemistry Accounts. 2000, 103(3-4), 242-7.
- Yarkony, David R. Substituent effects and the noncrossing rule: The importance of reduced symmetry subspaces. I. The quenching of OH (A2Σ+) by H2. Journal of Chemical Physics. 1999, 111(15), 6661-4.
- Yarkony, David R. Suppressing the geometric phase effect: Closely spaced seams of the conical intersection in Na3(2 2E’). Journal of Chemical Physics. 1999, 111(11), 4906-12.
- Sohlberg, Karl and Yarkony, David R. On the strongly bound B3Π state of the CAr van der Waals complex: Bonding and predissociation. Journal of Chemical Physics. 1999, 111(7), 3070-6.
- Sadygov, Rovshan G. and Yarkony, David R. Unusual conical intersections in the Jahn-Teller effect: The electronically excited states of Li3. Journal of Chemical Physics. 1999, 110(8), 3639-42.
- Parlant, Gerard and Yarkony, David R. A theoretical analysis of the state-specific decomposition of OH(A2Σ+,v’,N’,F1/F2) levels, including the effects of spin-orbit and Coriolis interactions. Journal of Chemical Physics. 1999, 110(1), 363-76.
- Yarkony, David R. Determining the molecular Aharonov-Bohm phase angle: A rigorous approach employing a molecular properties based adiabatic to diabatic states transformation. Journal of Chemical Physics. 1999, 110(2), 701-5.
- Yarkony, David R. S1-S0 Internal Conversion in Ketene. 1. The Role of Conical Intersections. Journal of Physical Chemistry A. 1999, 103(33), 6658-68.
- Yarkony, David R. Conical Intersections: Diabolical and Often Misunderstood. Accounts of Chemical Research. 1998, 31(8), 511-8.
- Yarkony, David R. Unanticipated confluences of seams of conical intersection: reinvestigating intersecting potential-energy surfaces using new tools. I. C(3P) + H2. Journal of Chemical Physics. 1998, 109(17), 7047-50.
- Sadygov, Rovshan G. and Yarkony, David R. On the adiabatic to diabatic states transformation in the presence of a conical intersection: A most diabatic basis from the solution to a Poisson’s equation. I. Journal of Chemical Physics. 1998, 109(1), 20-5.
- Gordon, Mark S.; Glezakou, Vassiliki-Alexandra; Yarkony, David R. Systematic location of intersecting seams of conical intersection in triatomic molecules: the 12A’-22A’ conical intersections in BH2. Journal of Chemical Physics. 1998, 108(14), 5657-9.
- Yarkony, David R. On the Construction of Diabatic Bases Using Molecular Properties. Rigorous Results in the Vicinity of a Conical Intersection. Journal of Physical Chemistry A 1998, 102(42), 8073-7.
- Yarkony, David R. On the Mechanism of the Spin-Nonconserving Chemical Reaction O(3P) + HCCH -> CH2(~a1A1) + CO(X1Σ +). I. Feasibility. Journal of Physical Chemistry A. 1998, 102(27), 5305-11.
- Yarkony, David R. On the description of potential energy surfaces exhibiting conical intersections: a compact representation of the energies and derivative couplings and locally diabatic bases for the HOH and OHH portions of the 11A’-21A’ seam of conical intersection in water. Molecular Physics. 1998, 93(6), 971-83.
- Matsunaga, Nikita and Yarkony, David R. Energies and derivative couplings in the vicinity of a conical intersection. 3. The ‘most’ diabatic basis. Molecular Physics. 1998, 93(1), 79-84.
- Kryachko, Eugene S. and Yarkony, David R. Quenching of Li(2P) by H2. Potential energy surfaces, conical intersection seam, and diabatic bases. Theoretical Chemistry Accounts 1998, 100(1-4), 154-70.
- Matsunaga, Nikita and Yarkony, David R. Energies and derivative couplings in the vicinity of a conical intersection. II. CH2(2 3A”,3 3A”) and H2S(1 1A”,2 1A”), unexpected results in an ostensibly standard case. Journal of Chemical Physics. 1997, 107(19), 7825-38.
- Sohlberg, Karl and Yarkony, David R. On the origin of the heavy atom effect in the fine-structure splitting of the 12Pi state of alkali metal 2P-rare gas van der Waals molecules. Journal of Chemical Physics. 1997, 107(19), 7690-4.
- Sadygov, Rovshan G. and Yarkony, David R. Electronic structure aspects of the spin-forbidden reaction CH3(X 2A2”)+ N(4S)->HCN(X1 Σ +)+ H2(X1Σg +). Journal of Chemical Physics. 1997, 107(13), 4994-9.
- Sohlberg, Karl and Yarkony, David R. A theoretical investigation of the spin-orbit-induced predissociation of BAr C2Δ. Journal of Chemical Physics. 1997, 106(16), 6607-11.
- Sadygov, Rovshan G.; Rostas, Joelle; Taieb, Guy; Yarkony, David R. Resonances in the predissociation of the A2ΠΩ state of MgBr. Journal of Chemical Physics. 1997, 106(10), 4091-101.
- Sohlberg, Karl and Yarkony, David R. On the Relation between Bonding and the Spin-Orbit Interaction in BNe: the C2Δ and 14Π States. Journal of Physical Chemistry A. 1997, 101(49), 9520-4.
- Chaban, Galina; Gordon, Mark S.; Yarkony, David R. The Reactions Al(2P) + H2 -> AlH2(12A’, 22A’) -> AlH2(X2A1) or AlH(X1Σ+) + H: Unusual Conical Intersections and Possible Nonadiabatic Recrossing. Journal of Physical Chemistry A. 1997, 101(43), 7953-9.
- Yarkony, David R. Energies and Derivative Couplings in the Vicinity of a Conical Intersection Using Degenerate Perturbation Theory and Analytic Gradient Techniques. Journal of Physical Chemistry A. 1997, 101(23), 4263-70.
- Sohlberg, Karl and Yarkony, David R. New and Unusual Bonding in Open Shell van der Waals Molecules Revealed by the Heavy Atom Effect: The Case of BAr. Journal of Physical Chemistry A. 1997, 101(17), 3166-73.
- Yarkony, David R. A criterion for the confluence of two seams of conical intersection in triatomic molecules. Theoretical Chemistry Accounts. 1997, 98(4), 197-201.
- Yarkony, David R. On the consequences of nonremovable derivative couplings. I. The geometric phase and quasidiabatic states: a numerical study. Journal of Chemical Physics. 1996, 105(23), 10456-61.
- Yarkony, David R. On the role of conical intersections in photodissociation. V. Conical intersections and the geometric phase in the photodissociation of methyl mercaptan. Journal of Chemical Physics. 1996, 104(20), 7866-81.
- Yarkony, David R. On the role of conical intersections in photodissociation. IV. Conical intersections and the geometric phase in the 23A” and 33A” states of CH2. Journal of Chemical Physics. 1996, 104(8), 2932-9.
- Yarkony, David R. Current Issues in Nonadiabatic Chemistry. Journal of Physical Chemistry. 1996, 100(48), 18612-28.
- Yarkony, David R. Quenching of CH(a4Σ-) by CO(X1Σ+): Surfaces of Intersection, Spin-Orbit Interactions, and the Incorporation of Kramers’ Degeneracy. Journal of Physical Chemistry. 1996, 100(44), 17439-45.
- Yang, Xin; Pederson, Lisa; Yarkony, David R.; Dagdigian, Paul J. Radiative and Nonradiative Decay of the BH(b3Σ-) State: A Joint Experimental and Theoretical Study. Journal of Physical Chemistry. 1996, 100(14), 5649-53.
- Han, Seungsuk and Yarkony, David R. Radiative and radiationless decay of multichannel resonances resulting from electronically non-adiabatic interactions: a computational approach valid for both narrow and broad line-widths and large energy shifts. Molecular Physics. 1996, 88(1), 53-68.
- Yarkony, David R. Diabolical conical intersections. Reviews of Modern Physics. 1996, 68(4), 985-1013.

**2021**

**Postdoctoral Research Associate**

Yafu Guan

**Graduate Students**

- Yuchen Wang
- Yifan Shen

**2016**

**Graduate Student**

Chris Malbon

**Summer Student**

James Xu

**2015**

**Postdoctoral Research Associate**

Xiaolei Zhu

**Graduate Student**

Chris Malbon

**2014**

**Postdoctoral Research Associate**

Joseph Dillon

**Graduate Students**

- Xiaolei Zhu
- Chris Malbon