Cioslowski Jerzy, Strasburger Krzysztof
Institute of Physics, University of Szczecin, Wielkopolska 15, 70-451 Szczecin, Poland.
Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Straaae 38, 01187 Dresden, Germany.
J Chem Theory Comput. 2024 Sep 3;20(18):7876-83. doi: 10.1021/acs.jctc.4c00533.
The values of the one-electron and intracule densities at two-particle coalescence points that enter the expressions for relativistic corrections to energies of Coulombic systems cannot be efficiently computed with sufficient accuracy from approximate wave functions expressed in terms of cuspless basis functions such as the explicitly correlated Gaussians. A new approach to alleviation of this problem, called plain capping, is proposed. Unlike those offered by the previously published formalisms, such as the expectation value identities and integral transforms, the accuracy improvements effected by the plain capping are attained with negligible computational effort and minimum programming. In the case of the on-top two-electron densities, whose accurate computation is particularly costly, the plain capping constitutes the only viable means of error reduction available at present.
进入库仑系统能量相对论修正表达式的两粒子合并点处的单电子密度和内禀密度值，无法通过用诸如显式相关高斯函数等无尖点基函数表示的近似波函数，以足够的精度有效地计算出来。本文提出了一种缓解该问题的新方法，称为普通封顶法。与先前发表的形式主义方法（如期望值恒等式和积分变换）不同，普通封顶法实现的精度提高只需付出可忽略不计的计算量和最少的编程工作。对于精确计算成本特别高的顶对顶双电子密度情况，普通封顶法是目前唯一可行的减少误差的方法。
