Giese Timothy J, York Darrin M
Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA.
J Chem Phys. 2005 Oct 22;123(16):164108. doi: 10.1063/1.2080007.
The present work outlines a new method for treatment of charge-dependent polarizability in semiempirical quantum models for use in combined quantum-mechanical/molecular mechanical simulations of biological reactions. The method addresses a major shortcoming in the performance of conventional semiempirical models for these simulations that is tied to the use of a localized minimal atomic-orbital basis set. The present approach has the advantages that it uses a density basis that retains a set of linear-response equations, does not increase the atomic-orbital basis, and avoids the problem of artificial charge transfer and scaling of the polarizability seen in related models that allow atomic charges to fluctuate. The model introduces four new atom-based parameters and has been tested with the modified neglect of differential overlap d-orbital Hamiltonian against 1132 molecules and ions and shown to decrease the dipole moment and polarizability errors by factors of 2 and 10, respectively, with respect to density-functional results. The method performs impressively for a variety of charge states (from 2+ to 2-), and offers a potentially powerful extension in the design of next generation semiempirical quantum models for accurate simulations of highly charged biological reactions.
本工作概述了一种用于半经验量子模型中电荷依赖极化率处理的新方法，该模型用于生物反应的量子力学/分子力学联合模拟。该方法解决了传统半经验模型在这些模拟中性能的一个主要缺点，这个缺点与使用局域最小原子轨道基组有关。本方法具有以下优点：它使用了保留一组线性响应方程的密度基，不增加原子轨道基，并且避免了在允许原子电荷波动的相关模型中出现的人工电荷转移和极化率缩放问题。该模型引入了四个新的基于原子的参数，并已用修正的忽略微分重叠d轨道哈密顿量对1132个分子和离子进行了测试，结果表明，相对于密度泛函结果，偶极矩和极化率误差分别降低了2倍和10倍。该方法在各种电荷状态（从2+到2-）下都表现出色，并为下一代用于精确模拟高电荷生物反应的半经验量子模型的设计提供了潜在的有力扩展。
