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. 2012 Oct 14;137(14):144101. doi: 10.1063/1.4757263.
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)], which is based on the locality of relativistic effects, has been extended to a four-component Dirac-Coulomb Hamiltonian. In the previous study, the LUT scheme was applied only to a one-particle IODKH Hamiltonian with non-relativistic two-electron Coulomb interaction, termed IODKH/C. The current study extends the LUT scheme to a two-particle IODKH Hamiltonian as well as one-particle one, termed IODKH/IODKH, which has been a real bottleneck in numerical calculation. The LUT scheme with the IODKH/IODKH Hamiltonian was numerically assessed in the diatomic molecules HX and X(2) and hydrogen halide molecules, (HX)(n) (X = F, Cl, Br, and I). The total Hartree-Fock energies calculated by the LUT method agree well with conventional IODKH/IODKH results. The computational cost of the LUT method is reduced drastically compared with that of the conventional method. In addition, the LUT method achieves linear-scaling with respect to the system size and a small prefactor.
基于相对论效应局域性的无自旋无穷阶 Douglas-Kroll-Hess（IODKH）局域变换（LUT）方案[J. Seino 和 H. Nakai, J. Chem. Phys. 136, 244102 (2012)]已扩展到四分量 Dirac-Coulomb 哈密顿量。在之前的研究中，LUT 方案仅应用于具有非相对论双电子库仑相互作用的单粒子 IODKH 哈密顿量，称为 IODKH/C。本研究将 LUT 方案扩展到单粒子和双粒子 IODKH 哈密顿量，称为 IODKH/IODKH，这一直是数值计算的真正瓶颈。在双原子分子 HX 和 X(2)和卤化氢分子 (HX)(n)（X = F、Cl、Br 和 I）中，对具有 IODKH/IODKH 哈密顿量的 LUT 方案进行了数值评估。LUT 方法计算的哈特ree-Fock 总能量与传统的 IODKH/IODKH 结果吻合良好。与传统方法相比，LUT 方法的计算成本大大降低。此外，LUT 方法在系统规模上呈线性缩放，并具有较小的前置因子。
