Local explicit correlation methods

局部显式相关方法

• 批准号: 16727211
• 负责人: Professor Dr. Hans-Joachim Werner
• 金额: --
• 依托单位: Institut für Theoretische Chemie (ITheoC)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/16727211?language=en
• 关键词: Local; explicit; correlation; methods

The aim of the current project is to improve the basis set convergence in local coupled cluster methods by including r12-dependent correlation factors. The methods should be applicable to molecules with 50-100 atoms and yield accurate results with medium-size basis sets. In the first funding period explicitly correlated methods based on closed-shell local M011er-Plesset perturbation theory (LMP2) were successfully developed. These will now be extended to restricted open-shell LMP2 and (approximate) coupled cluster methods. As before, Slater functions (approximated by fixed contractions of Gaussian Geminals) will be used in the correlation factor (F12 methods), but the ansatz will be extended to allow for the use of two or more Slater functions with different exponents. This will provide the additional flexibility that is probably needed to treat core correlation effects or heavier elements. All required integrals will be evaluated using density fitting approximations. The accuracy the new methods will be systematically investigated by computing thermodynamic quantities such as reaction energies, ionization potentials, electron affinities, as well as interaction energies of molecular clusters.

目前的项目的目的是提高基组收敛局部耦合集群方法，包括r12相关因子。该方法应适用于具有50-100个原子的分子，并在中等大小的基组下产生准确的结果。在第一个资助期内，成功开发了基于闭壳层局部M011 er-Plesset扰动理论（LMP 2）的明确相关方法。现在将这些方法扩展到受限开壳层LMP 2和（近似）耦合簇方法。如前所述，斯莱特函数（由高斯双子的固定收缩近似）将用于相关因子（F12方法），但将扩展该系数以允许使用具有不同指数的两个或多个斯莱特函数。这将提供额外的灵活性，可能需要处理核心相关效应或较重的元素。将使用密度拟合近似法评价所有要求的积分。新方法的准确性将通过计算热力学量，如反应能，电离势，电子亲合势，以及分子团簇的相互作用能进行系统的研究。