Accurate and robust wavefunction methods for energies andstructures of electronically excites states in complex systems

用于复杂系统中电子激发态的能量和结构的准确而鲁棒的波函数方法

• 批准号: 230935766
• 负责人: Professor Dr. Christof Hättig
• 金额: --
• 依托单位: Lehrstuhl für Theoretische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/230935766?language=en
• 关键词: Accurate; robust; wavefunction; methods; energies

Methods based on second-order perturbation theory as the approximate coupled-cluster singles-and-doubles model CC2 are widely applied for the prediction of UV/Vis spectra and potential energy surfaces for excited states. They are often the only tractable first principles approaches if time-dependent density functional theory is not applicable because charge-transfer processes are involved. For systems beyond 100 atoms, the use of these methods is hampered by their steep cost-scaling.Another limitation are large errors for doubly excited states and if strong correlation effects are encountered in the ground state. These problems can very often be overcome with the full coupled-cluster singles-and-doubles (CCSD) and the approximate triples model CC3, which have, however, an even steeper cost-scaling.In this project we will develop an implementation of the hierarchy CC2, CCSD, CC3 and approximations to these with reduced computational costs and apply them for systems relevant for photoelectrochemical cells, which are challenging for currently available methods. To achieve a robust accuracy we only apply approximations based on the analysis of wavefunction and energy diagnostics.

基于二阶微扰理论的近似耦合团簇单双模型CC 2方法被广泛应用于预测紫外/维斯光谱和激发态势能面。如果因涉及电荷转移过程而不适用时变密度泛函理论，它们通常是唯一易于处理的第一原理方法。对于超过100个原子的系统，这些方法的使用受到其陡峭的成本标度的阻碍。另一个限制是双激发态的大误差，如果在基态遇到强关联效应。这些问题通常可以用完全耦合簇单双模型（CCSD）和近似三重模型CC 3来克服，然而，它们具有更陡峭的成本缩放。在这个项目中，我们将开发一个层次CC 2，CCSD，CC 3和近似的实现，以降低计算成本，并将它们应用于光电化学电池相关的系统，这对于当前可用的方法是具有挑战性的。为了实现稳健的精度，我们只应用基于波函数分析和能量诊断的近似。