**Bio:**

Alexander Sokolov received his Specialist (M.Sc.) degree in Chemistry from Saint Petersburg State University (Russia) in 2009, where he worked with Prof. Olga Sizova on developing computational techniques for understanding and quantifying the strength of the chemical bonds in transition metal complexes. Alexander earned his Ph.D. in Chemistry from the University of Georgia in 2014, where he worked in the group of Prof. Henry Schaefer at the Center for Computational Quantum Chemistry. There, his research was focused on the computational studies of molecules with complex electronic structure (radicals, transition metal complexes, molecules in electronically-excited states), as well as the development of new electronic structure methods for the accurate prediction of molecular properties. In August 2014, Alexander began his postdoctoral work at Princeton University in the group of Prof. Garnet Chan, where he developed several accurate and efficient methods for the description of strong electron correlation in molecules. In July 2016, Alexander moved to California, where he continued his postdoc in the group of Prof. Garnet Chan at the California Institute of Technology. Alexander joined the Department of Chemistry and Biochemistry at the Ohio State University in August 2017 as an Assistant Professor.

**Research Overview:**

Research in the Sokolov group aims to develop new theoretical methods for the simulations of light-induced and non-equilibrium processes in chemical systems with complex electronic structure. Our specific focus is the development of new electronic structure approaches that can efficiently describe electron correlation effects and charge/energy transfer in many (10's or even 100's) electronic states. Our group’s method development is driven by the study of transition metal photochemistry, electron transfer in photocatalytic systems, and non-equilibrium electron dynamics in molecular electronic devices. Members of the Sokolov group will receive rigorous training in computational and quantum chemistry and will acquire valuable technical skills in scientific software development.

**1) Accurate electronic structure in many electronic states**

Reliable predictions of how molecules react with light are essential for designing new photoactive materials with desired properties. However, modelling photochemical reactions is very challenging, as it requires considering many electronic states and strong electron correlation effects that originate due to significant mixing of degenerate (or near-degenerate) electronic configurations. An accurate description of strong correlation is critical to simulate crossings of electronic states and bond breaking, which are responsible for the vast majority of photochemical transformations. Our lab aims to develop new methods for excited states that accurately describe effects of strong electron correlation, yet crucially are computationally affordable in large systems (e.g., transition metal compounds). We are particularly interested in developing multi-state approaches that efficiently describe electronic structure of molecules in many electronic states simultaneously. Our ultimate goal is to apply the computational tools developed in our group to problems in biology and medicine. Some examples include photoinduced release of small bioactive molecules (e.g., NO or CO) and photoactivation of novel metal-based drugs important in photochemotherapy.

**2) Nonadiabatic dynamics in photocatalytic systems**

While many photochemical reactions require ultraviolet radiation, there is a growing interest in exploiting visible light in chemical synthesis. Recent advances in photoredox catalysis have led to the development of new photocatalyzed reactions that produce complex organic compounds under visible-light irradiation. These photocatalyzed transformations are initiated by the absorption of light by a catalyst (typically, a transition metal complex), followed by the transfer of energy or electrons between the catalyst and a substrate. Our group aims to develop methodology that will be able to simulate electronic structure, nuclear dynamics, and electron transfer in a photocatalytic system from first-principles. This requires finding efficient ways to describe electronic structure, dynamics of the nuclei and electrons, as well as nonadiabatic effects due to the coupling of the nuclear and electronic motion. A popular approach to nonadiabatic dynamics is to use semiclassical methods that describe nuclear motion with classical mechanics and simulate nonadiabatic effects as stochastic transitions between potential energy surfaces. In these simulations, the key bottleneck, which currently prohibits the application of semiclassical methods to photocatalytic systems, is the computation of potential energy surfaces that must be performed many (100's to 1000's) times along the molecular dynamics trajectories. Our group will develop new approaches that can very efficiently compute potential energy surfaces by compressing electronic structure information from accurate first-principles simulations. We plan to use these approaches to investigate nonadiabatic dynamics in photocatalytic systems.

**3) Non-equilibrium electron transport in correlated systems**

Accurate simulation of the non-equilibrium electron dynamics in molecular systems is of fundamental importance and has many potential applications in the design of molecular electronic devices. Conducting molecular systems offer significant advantages on cost, scalability, component density, and power consumption criteria. However, at the fundamental level, the non-equilibrium dynamics of electrons in molecular systems remains to be poorly understood. Our group aims to develop new theoretical approaches that will enable accurate fully atomistic simulations of electron transport in molecular systems with first-principles quantum-mechanical methods. Using these new approaches, we will be able to investigate mechanisms and kinetics of electron transport in molecules where electron correlation is very important and predict properties of novel types of molecular electronic devices directly from computation.

*The Sokolov lab is currently looking for highly enthusiastic and motivated graduate and undergraduate students interested in developing and applying computational methods to study the electronic structure, nonadiabatic dynamics, and non-equilibrium electron transport in complex molecular systems. *

**Selected Publications:**

"Multi-reference algebraic diagrammatic construction theory for excited states: General formulation and first-order implementation", **A. Yu. Sokolov**, J. Chem. Phys. **149**, 204113 (2018).

"Linear-response density cumulant theory for excited electronic states", A. V. Copan and **A. Yu. Sokolov**, J. Chem. Theory Comput. **14**, 4097 (2018).

"Time-dependent N-electron valence perturbation theory with matrix product state reference wavefunctions for large active spaces and basis sets: Applications to the chromium dimer and all-trans polyenes", **A. Yu. Sokolov**, S. Guo, E. Ronca, and G. K.-L. Chan, J. Chem. Phys. **146**, 244102 (2017).

"Spin-adapted formulation and implementation of density cumulant functional theory with density-fitting approximation: Application to transition metal compounds", X. Wang, **A. Yu. Sokolov**, J. M. Turney, and H. F. Schaefer, J. Chem. Theory Comput. **12**, 4833 (2016).

"A time-dependent formulation of multi-reference perturbation theory", **A. Yu. Sokolov** and G. K.-L. Chan, J. Chem. Phys. **144**, 064102 (2016).

"Can density cumulant functional theory describe static correlation effects?", J. W. Mullinax, **A. Yu. Sokolov**, and H. F. Schaefer, J. Chem. Theory Comput. **11**, 2487 (2015).

"A transformed framework for dynamic correlation in multireference problems", **A. Yu. Sokolov** and G. K.-L. Chan,J. Chem. Phys. **142**, 124107 (2015).

"Density cumulant functional theory from a unitary transformation: N-representability, three-particle correlation effects, and application to O4+", **A. Yu. Sokolov**, H. F. Schaefer, and W. Kutzelnigg, J. Chem. Phys. **141**, 074111 (2014).

"Orbital-optimized density cumulant functional theory", **A. Yu. Sokolov**, and H. F. Schaefer, J. Chem. Phys. **139**, 204110 (2013).

"Free cyclooctatetraene dianion: planarity, aromaticity, and theoretical challenges", **A. Yu. Sokolov**, D. B. Magers,J. I. Wu, W. D. Allen, P. v. R. Schleyer, and H. F. Schaefer, J. Chem. Theory Comput. **9**, 4436 (2013).

"Density cumulant functional theory: the DC-12 method, an improved description of the one-particle density matrix", **A. Yu. Sokolov**, A. C. Simmonett, and H. F. Schaefer, J. Chem. Phys. **138**, 024107 (2013).

"Analytic gradients for density cumulant functional theory: the DCFT-06 model", **A. Yu. Sokolov**, J. J. Wilke,A. C. Simmonett, and H. F. Schaefer, J. Chem. Phys. **137**, 054105 (2012).

"Ground and excited state properties of photoactive platinum(IV) diazido complexes: theoretical considerations", **A. Yu. Sokolov**, and H. F. Schaefer, Dalton Trans. **40**, 7571 (2011).