Köppl Christoph, Werner Hans-Joachim
Institut für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
J Chem Phys. 2015 Apr 28;142(16):164108. doi: 10.1063/1.4918772.
Electron correlation methods based on symmetry-adapted canonical Hartree-Fock orbitals can be speeded up significantly in the well known group theoretical manner, using the fact that integrals vanish unless the integrand is totally symmetric. In contrast to this, local electron correlation methods cannot benefit from such simplifications, since the localized molecular orbitals (LMOs) generally do not transform according to irreducible representations of the underlying point group symmetry. Instead, groups of LMOs become symmetry-equivalent and this can be exploited to accelerate local calculations. We describe an implementation of such a symmetry treatment for density-fitted local Møller-Plesset perturbation theory, using various types of virtual orbitals: Projected atomic orbitals, orbital specific virtuals, and pair natural orbitals. The savings by the symmetry treatment are demonstrated by calculations for several large molecules having different point group symmetries. Benchmarks for the parallel execution efficiency of our method are also presented.
基于对称适配规范哈特里-福克轨道的电子相关方法，可以以众所周知的群论方式显著加速，这是利用了除非被积函数完全对称，否则积分值为零这一事实。与此相反，局部电子相关方法无法从这种简化中受益，因为局域分子轨道（LMO）通常不会按照基础点群对称的不可约表示进行变换。相反，LMO的组会变得对称等效，并且可以利用这一点来加速局部计算。我们描述了一种针对密度拟合局部莫勒-普莱塞特微扰理论的对称处理实现方法，使用了各种类型的虚拟轨道：投影原子轨道、轨道特定虚拟轨道和对自然轨道。通过对具有不同点群对称性的几个大分子进行计算，展示了对称处理带来的节省。还给出了我们方法并行执行效率的基准测试。
