Research Interests


Theoretical/Computational Chemistry (as well as Physics) plays an important role in the rapid development of modern technologies such as nanotechnology and biotechnology. So far it has provided a nice explanation to the origin of various experimental results. Moreover, theoretical works can suggest possible candidates for future functional materials based on theoretical foundations. Many methods have been developed in theoretical/computational chemistry, but most of them focus on the static (or ground state) properties of materials such as a binding energy, a ground state electronic density, and so on. They just fix the nuclear position, and then they calculate the ground state energy and electronic density. Even if nuclei move, they consider the nuclei just movig on the ground state surface. The basic idea here is that nuclei move much slower than electrons. Then, nuclei move along the potential generated by the fast moving electrons as they are uncorrelated. These methods are very limited to more dynamial processes like a chemical reaction with an extra energy and the light-matter interaction because the electron-nuclear correlation plays a major role. Such cases are called as excited state phenomena which are actually ubiquitous in nature like vision process and photosynthesis. In our group, we are interested in the theoretical/computational description of excited state phenomena and its applications.

Research Interests

Development of a novel mixed quantum-classical algorithm for excited state molecular dynamics

To understand various interesting phenomena such as charge transfer, exciton transfer, polaron transfer, and (non)radiative decays in photovoltaics, photochemistry, polaron chemistry, and photocatalysts, it is extremely crucial to understand molecular processes with light-matter interactions. The most accurate description for these processes would be the fully quantum mechanical dynamics by solving the time-dependent Schrodinger equation or the quantum Liouville equation, which is possible only for the small degrees of freedom. One of the most promising approaches is the so-called mixed quantum-classical dynamics which deals with the electronic and nuclear degrees of freedom based on quantum mechanics and classical mechanics, respectively. In this case, the most crucial part is to understand the correlation between electrons and nuclei. My group investigates and develops various mixed quantum-classical approaches based on the exact factorization which can deal with the exact electron-nuclear correlation.

Related papers:

Surface Hopping Dynamics beyond Nonadiabatic Couplings for Quantum Coherence, Ha, J.-K.; Lee, I.S.; Min, S.K., J. Phys. Chem. Lett., 9, 1097-1104, 2018

Direct Non-Adiabatic Dynamics by Mixed Quantum-Classical Formalism Connected with Ensemble Density Functional Theory Method: Application to trans-Penta-2,4-Dieniminium Cation, Filatov, M; Min, S.K.;Kim, K.S., J. Chem. Theory Comput., 14, 4499-4512, 2018

PyUNIxMD: A Python-based excited state molecular dynamics package, Lee, I.S.; Ha, J.-K.; Han, D.; Kim, T.I.; Moon, S.W.; Min, S.K., J. Comp. Chem. 42, 1755-1766, 2021

Code development - pyUNIxMD

One of the codes developed from my group is "pyUNIxMD" which can perform excited state molecular dynamics simulations based on various mixed quantum-classical algorithm. "pyUNIxMD" is under the active development. Various novel approaches to describe photochemical reactions in molecular systems and extended systems are soon to be updated.

Related papers:

PyUNIxMD: A Python-based excited state molecular dynamics package, Lee, I.S.; Ha, J.-K.; Han, D.; Kim, T.I.; Moon, S.W.; Min, S.K., J. Comp. Chem. 42, 1755-1766, 2021

Development of excited state electronic structure calculations

One of the most important to simulate excited state molecular dynamics is the efficient and accurate quantum chemical calculations for electronic excited states. Since the quantum chemical calculation is the most time-consuming part, the development of efficient quantum chemical methods is really demanding. My research group tries to develop semi-empirical approaches and machine learning approaches to calculate potential energy surfaces for excited state molecular dynamics.

Related papers:

Machine Learning-Assisted Excited State Molecular Dynamics with the State-Interaction State-Averaged Spin-Restricted Ensemble-Referenced Kohn–Sham Approach, Ha, J.-K.;Kim, K; Min, S.K., J. Chem. Theory Comput., 17, 694-702, 2021

Formulation and Implementation of the Spin-Restricted Ensemble-Referenced Kohn-Sham Method in the Context of the Density Functional Tight Binding Approach, Lee, I.S.;Filatov, M;Min, S.K., J. Chem. Theory Comput., 15, 3021-3032, 2019

DFTB+, a software package for efficient approximate density functional theory based atomistic simulations, Lee, I.S., Min, S.K. et. al. as co-authors, J. Chem. Phys. 152, 124101, 2020

Design of multi-functional molecular devices

As an application of theoretical/computational chemistry, we can design functional molecular/nano-sized devices such as novel DNA sequencing device, molecular sensors, molecular photoswitching device, molecular photonic devices, photosynthetic materials, and so on.

Related papers:

Fulgides as Light-Driven Molecular Rotary Motors: Computational Design of a Prototype Compound, Filatov, M; Min, S. K.; Kim, K. S., J. Phys. Chem. Lett., 9, 4995-5001, 2018

Design and photoisomerization dynamics of a new family of synthetic 2-stroke light driven molecular rotary motors, Filatov, M; Paolino, M; Min, S.K.; C.H. Choi, Chem. Comm., 55, 5247-5250, 2019

Fast DNA sequencing with a graphene-based nanochannel device, Min, S.K.; Kim, W.Y.; Cho, Y.; Kim, K.S., Nat. Nanotechnol., 6, 162-165, 2011

Material chemistry-related

Computational chemistry is a great tool to understand underlying mechanisms at the molecular level to unveil the chemical reactions or chemical/physical processes in material chemistry. For example, our group is in collaborations with many experimental groups.

Related papers:

Metal-organic framework based on hinged cube tessellation as transformable mechanical metamaterial, Jin, E.; Lee, I.S.; Kim, D.; Lee, H.; Jang, W.-D.; Lah, M.S.; Min, S.K.; Choe, W., Sci. Adv., 5, eaav4119, 2019

Effect of Pt Crystal Surface on Hydrogenation of Monolayer h-BN and Its Conversion to Graphene, Kim, M.; Moon, S.W.; Kim, G.;Yoon, S.I.;Kim, K.;Min, S.K.;Shin, H.S., Chem. Mater., 32, 4584-4590, 2020