Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
J Chem Phys. 2013 Jul 21;139(3):034109. doi: 10.1063/1.4813595.
In order to perform practical electron correlation calculations, the local unitary transformation (LUT) scheme at the spin-free infinite-order Douglas-Kroll-Hess (IODKH) level [J. Seino and H. Nakai, J. Chem. Phys. 136, 244102 (2012); and ibid. 137, 144101 (2012)], which is based on the locality of relativistic effects, has been combined with the linear-scaling divide-and-conquer (DC)-based Hartree-Fock (HF) and electron correlation methods, such as the second-order Mo̸ller-Plesset (MP2) and the coupled cluster theories with single and double excitations (CCSD). Numerical applications in hydrogen halide molecules, (HX)n (X = F, Cl, Br, and I), coinage metal chain systems, Mn (M = Cu and Ag), and platinum-terminated polyynediyl chain, trans,trans-{(p-CH3C6H4)3P}2(C6H5)Pt(C≡C)4Pt(C6H5){(p-CH3C6H4)3P}2, clarified that the present methods, namely DC-HF, MP2, and CCSD with the LUT-IODKH Hamiltonian, reproduce the results obtained using conventional methods with small computational costs. The combination of both LUT and DC techniques could be the first approach that achieves overall quasi-linear-scaling with a small prefactor for relativistic electron correlation calculations.
为了进行实用的电子相关计算，我们将基于相对论效应局域性的无自旋无限阶 Douglas-Kroll-Hess（IODKH）水平的局部幺正变换（LUT）方案[J. Seino 和 H. Nakai，J. Chem. Phys. 136, 244102（2012）；以及同上，137, 144101（2012）]，与基于分治（DC）的线性标度 Hartree-Fock（HF）和电子相关方法（如二阶 Mo̸ller-Plesset（MP2）和单激发和双激发的耦合簇理论（CCSD））相结合。在氢卤化物分子（HX）n（X = F，Cl，Br 和 I）、金属链系统（Mn，M = Cu 和 Ag）和末端为铂的聚乙炔链，trans,trans-{(p-CH3C6H4)3P}2(C6H5)Pt(C≡C)4Pt(C6H5){(p-CH3C6H4)3P}2 中的数值应用表明，本方法（即 DC-HF、MP2 和具有 LUT-IODKH 哈密顿量的 CCSD）以较小的计算成本再现了使用传统方法获得的结果。LUT 和 DC 技术的结合可能是实现相对论电子相关计算整体准线性标度的第一种方法，其小的前因子。
