Accurate Force Field Development for Modelling Macromolecular Assemblies Containing Diketopyrrolopyrrole and Thiophene
作者单位：宁波诺丁汉大学 School of Chemistry University of Nottingham Department of Chemical and Environmental Engineering University of Nottingham Ningbo China
会议名称：《2019中国化学会第十五届全国计算（机）化学学术会议》
会议日期：2019年
学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 070303[理学-有机化学] 0703[理学-化学]
关 键 词：Conjugated Molecules Force Fields Development Force-Matching Molecular Dynamics Simulation
摘 要：It is challenging to find sufficiently accurate force fields for applications where equilibrium structures generated from classical molecular dynamics simulations are employed in post quantum chemistry calculations.1 One particular application is in the study of optical and electronic properties of materials and biomolecules. Many semiconducting polymers, molecular crystals and biological chromophores of interest exhibit complex chemical structures with extended-conjugation that prevent the use of standard force fields. Furthermore, large conjugated molecules require to use many atom types and parameters. They also tend to be system specific in most cases and not transferable.2 Thus, parameterising force fields for conjugated systems using existing approaches can be time demanding. In addition, it is desirable that the equilibrium structures generated from classical molecular dynamics simulations are as close as possible to those that would have been generated using the same level of theory as the post electronic structure calculations. We present a scheme, utilising the force matching procedure,3,4 to systematically parameterise new force fields for large conjugated systems. We apply the method to both conjugated polymers and molecular crystals that contain diketopyrrolopyrrole（DPP） and thiophene units. These systems have recently been found to have low band gap, which exhibit high effciency for photovoltaic devices. We use the newly parameterised force fields to model these systems and our molecular dynamics simulation results will help in the understanding of the molecular level origins of the high-efficiency of these classes of materials.