Michael Herman

My research interests include the development and testing of semiclassical methods for systems involving transitions between molecular states and for systems where tunneling is important.  Semiclassical methods use information obtained from classical trajectories to provide a good approximation to the quantum mechanical description of molecular systems.

I am also using computer simulations to better understand the mechanisms for chain diffusion and stress relaxation in long chain polymer melts.  Of particular interest in these studies is elucidating the role of cooperative many chain motions.

A third area of current research aims at providing a better understanding of the propensities of different isotopes of an element to populate certain locations in a molecule.  In addition, a better understanding of how different isotopologues of a molecule, which have different isotopes at specific positions in the molecule, can alter phase equilibria.

Discipline

Physical Chemistry

Selected Publications

Azeotropic Isotopologues, R. P. Currier, T. B. Peery, M. F. Herman, R. Williams, R. Michalczyk, T. Larson, D. Labotka, J. Fessenden, and S. M. Clegg, Fluid Phase Equilibria, 493, 188-195(2018).

A Test of the Significance of Intermolecular Dipolar Vibrational Coupling in Isotopic Fractionation, M. F Herman, R, P. Currier, T. B. Peery, and S. M. Clegg, Chem. Phys. 494, 11-19 (2017).

Semiclassical Time Dependent Tunneling Using Real Trajectories, M. F. Herman, J. Chem. Phys. 143, 164110 (2015).

Surface Hopping, Transition State Theory and Decoherence 1: Scattering Theory and Time Reversibility, A. Jain, M. F. Herman, W. Ouyang, and J. E. Subotnik, J. Chem. Phys. 143, 134106 (2015).

Isotope Mass Effect on the Intermolecular Potential, M. F. Herman, R. P. Currier, and S. M. Clegg, Chem. Phys. Lett. 639, 266-268 (2015).

Analysis of a Surface Hopping Methods to Includes Hops in Classically Forbidden Regions, M. F. Herman, Chem. Phys. 433, 12 (2014).
 
Improving the Efficiency of Monte Carlo Surface Hopping Calculations, M. F. Herman, J. Phys. Chem. B. 118, 8026-8033 (2014).
 
A Justification for the Use of Approximate Transition Amplitudes in Semiclassical Surface, Phuong-Thanh  Dang and Michael F. Herman, Mol. Physics (2011)109(12) 1581-1592.

Erratum:  The Calculation of Multidimensional Semiclassical Wave Functions in the Forbidden Region Using Real Valued Coordinates, J. Chem. Phys. 134(8) 089901/1-089901/2.

Using Semiclassical Surface Hopping for Coupled Partial Wave Calculations on Systems with Non-Spherically Symmetric Potentials, M. F.
Herman, Chem. Phys. 373, 274-282 (2010).
 
The Calculation of Multidimensional Semiclassical Wave Functions in the Forbidden Region Using Real Valued Coordinates, M. F.  Herman, J. Chem. Phys. 133, 114108 (2010).

A Semiclassical Model for the Calculation of Nonadiabatic Transition Probabilities for Classically Forbidden Transitions, Phuong-Thanh
 Dang and Michael F. Herman, J. Chem. Phys. 130, 054107 (2009).
 
A Singularity Free Surface Hopping Expansion for the Multistate Wave Function, M. F. Herman, J. Chem. Phys. 131, 214108 (2009).
 
 MF Herman, Y Wu,  An Analysis Through Order   ℏ2 of a Surface Hopping Expansion of the Nonadiabatic Wave Function,  J. Chem. Phys., 128, 11405 (2008).

MF Herman, Higher Order Phase Corrected Transition Amplitudes for Time Dependent Semicalssical Surface Hopping Calculations, Chem Phys., 351, 51 (2008).