Implementation of Replica-Exchange Umbrella Sampling to the DFTB+ Simulation Package

Abstract

We have investigated the computational methods which combined the self-consistent-charge Density Functional based Tight Binding (DFTB) method[1] for fast calculations of quantum effects and the Replica-Exchange Umbrella Sampling (REUS)[2] for enhanced conformational sampling. One of the excellent QM-MD simulation package named DFTB+ does not have REUS method incorporated. We thus modified DFTB+ to include the REUS method. We will compare the results of DFTB+ calculations with those by another simulation package. We will present the two comparative results for proton transfer reactions in small molecules.[1] M. Elstner, D. Porezag, G. Jungnickel, J. Elsner, M. Haugk, Th. Frauenheim, S. Suhai, and G. Seifert, Phys. Rev. B 58, 7260 (1998).[2] Y. Sugita, A. Kitao, and Y. Okamoto, J. Chem. Phys. 113, 6042 (2000).