Kottmann Jakob S, Bischoff Florian A, Valeev Edward F
Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin-Adlershof, Germany.
Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, USA.
J Chem Phys. 2020 Feb 21;152(7):074105. doi: 10.1063/1.5141880.
An efficient representation of molecular correlated wave functions is proposed, which features regularization of the Coulomb electron-electron singularities via the F12-style explicit correlation and a pair-natural orbital factorization of the correlation components of the wave function expressed in the real space. The pair-natural orbitals are expressed in an adaptive multiresolution basis and computed directly by iterative variational optimization. The approach is demonstrated by computing the second-order Moller-Plesset energies of small- and medium-sized molecules. The resulting MRA-PNO-MP2-F12 method allows for the first time to compute correlated wave functions in a real-space representation for systems with dozens of atoms (as demonstrated here by computations on alkanes as large as CH), with precision exceeding what is achievable with the conventional explicitly correlated MP2 approaches based on the atomic orbital representations.
提出了一种分子相关波函数的有效表示方法，其特点是通过F12风格的显式相关对库仑电子-电子奇点进行正则化，并对实空间中表示的波函数的相关分量进行对自然轨道分解。对自然轨道用自适应多分辨率基表示，并通过迭代变分优化直接计算。通过计算中小分子的二阶莫勒-普莱斯特定能来证明该方法。由此产生的MRA-PNO-MP2-F12方法首次允许以实空间表示法计算具有数十个原子的系统的相关波函数（此处通过对高达CH的烷烃的计算证明），其精度超过了基于原子轨道表示法的传统显式相关MP2方法所能达到的精度。
