General Force-Field Parametrization Scheme for Molecular Dynamics Simulations of Conjugated Materials in Solution

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• 作者：Jack Wildman ; Peter Repiščák ; Martin J. Paterson ; Ian Galbraith
• 刊名：Journal of Chemical Theory and Computation
• 出版年：2016
• 出版时间：August 9, 2016
• 年：2016
• 卷：12
• 期：8
• 页码：3813-3824
• 全文大小：659K
• 年卷期：0
• ISSN：1549-9626

文摘

We describe a general scheme to obtain force-field parameters for classical molecular dynamics simulations of conjugated polymers. We identify a computationally inexpensive methodology for calculation of accurate intermonomer dihedral potentials and partial charges. Our findings indicate that the use of a two-step methodology of geometry optimization and single-point energy calculations using DFT methods produces potentials which compare favorably to high level theory calculation. We also report the effects of varying the conjugated backbone length and alkyl side-chain lengths on the dihedral profiles and partial charge distributions and determine the existence of converged lengths above which convergence is achieved in the force-field parameter sets. We thus determine which calculations are required for accurate parametrization and the scope of a given parameter set for variations to a given molecule. We perform simulations of long oligomers of dioctylfluorene and hexylthiophene in explicit solvent and find peristence lengths and end-length distributions consistent with experimental values.