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arXiv 1504.00243cond-mat.mtrl-sciphysics.chem-ph
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基于密度泛函的紧束缚方法中长程修正泛函的实现与基准测试

Implementation and benchmark of a long-range corrected functional in the density functional based tight-binding method

Vitalij Lutsker, Balint Aradi, Thomas A. Niehaus

摘要:

基于密度泛函的紧束缚方法(DFTB)弥补了第一性原理方法和经验方案之间的差距,在过去的几年中已经成为预测原子模拟的通用工具。这种方法的主要限制之一是对局部或梯度校正的交换相关泛函的限制。这不包括重要的一类混合或远程校正的泛函,这是有利的热化学,以及在振动,光电子和光谱的计算。目前的工作提供了一个详细的实施DFTB的远程校正功能在广义Kohn-Sham理论。我们应用该方法对一组有机分子的电离势和电子亲合势与原来的DFTB方法和更高层次的理论进行比较。新方案治愈了局部DFTB中发现的电场中的显著过极化,这与第一性原理密度泛函理论(DFT)中的功能依赖性平行。与此同时,如数值基准数据所证明的,相对于完整DFT计算的计算节省并没有受到损害。

英文摘要:

Bridging the gap between first principles methods and empirical schemes, the density functional based tight-binding method (DFTB) has become a versatile tool in predictive atomistic simulations over the past years. One of the major restrictions of this method is the limitation to local or gradient corrected exchange-correlation functionals. This excludes the important class of hybrid or long-range corrected functionals, which are advantageous in thermochemistry, as well as in the computation of vibrational, photoelectron and optical spectra. The present work provides a detailed account of the implementation of DFTB for a long-range corrected functional in generalized Kohn-Sham theory. We apply the method to a set of organic molecules and compare ionization potentials and electron affinities with the original DFTB method and higher level theory. The new scheme cures the significant overpolarization in electric fields found for local DFTB, which parallels the functional dependence in first principles density functional theory (DFT). At the same time the computational savings with respect to full DFT calculations are not compromised as evidenced by numerical benchmark data.

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