Physics Department, Sofia University, 1164 Sofia, Bulgaria.
J Chem Phys. 2011 Jul 28;135(4):044120. doi: 10.1063/1.3615061.
Here the recently proposed time-dependent quantum Monte Carlo method is applied to three dimensional para- and ortho-helium atoms subjected to an external electromagnetic field with amplitude sufficient to cause significant ionization. By solving concurrently sets of up to 20,000 coupled 3D time-dependent Schrödinger equations for the guide waves and corresponding sets of first order equations of motion for the Monte Carlo walkers we obtain ground state energies in close agreement with the exact values. The combined use of spherical coordinates and B-splines along the radial coordinate proves to be especially accurate and efficient for such calculations. Our results for the dipole response and the ionization of an atom with un-correlated electrons are in good agreement with the predictions of the conventional time-dependent Hartree-Fock method while the calculations with correlated electrons show enhanced ionization that is due to the electron-electron repulsion.
这里应用了最近提出的时变量子蒙特卡罗方法，对处于足够大的外电磁场中的三维Para 和 Ortho 氦原子进行了研究，该场强足以导致显著的电离。通过同时求解多达 20000 组 3D 时变薛定谔方程的导引波，以及相应的第一类蒙特卡罗行走者运动方程，我们得到了与精确值非常吻合的基态能量。对于这种计算，使用球坐标和沿径向坐标的 B 样条证明是特别准确和有效的。我们对具有非关联电子的原子的偶极子响应和电离的结果与传统的时变哈特ree-fock 方法的预测非常吻合，而对于关联电子的计算则显示出增强的电离，这是由于电子-电子排斥所致。
