摘要
本文通过引进一组正交的辅助非活性轨道和与它正交的辅助活性轨道,将价键理论方法中的冻核近似推广到轨道非正交的情形,得到了体系能量及其对非活性轨道的梯度解析表达式,简化了价键自洽场方法中非正交轨道能量梯度的计算.该方法的标度为(Na+1)m4,其中Na和m分别是活性轨道和基函数的个数.分析表明,与现有的其他算法相比较,该方法具有更低的计算标度,因而计算效率更高.
This paper presents an efficient algorithm for energy gradients in valence bond self-consistent field (VBSCF) method with non-orthogonal orbitals. The frozen core approximation method is extended to the case of non-orthogonal orbitals. The expressions for the total energy and its gradients are presented by introducing auxiliary orbitals, where inactive orbitals are orthogonal, while active orbitals are non-orthogonal themselves but orthogonal to inactive orbitals. It is shown that our new algorithm has a low scaling of (Na+1)m^4, where Na and m are the numbers of the active orbitals and basis functions, respectively, and is more efficient than the existing VBSCF algorithms.
出处
《中国科学(B辑)》
EI
CSCD
北大核心
2009年第11期1424-1429,共6页
Science in China(Series B)
基金
国家自然科学基金项目(批准号:20533020,20873106)
国家基础研究计划(编号:204CB719902)资助
关键词
价键理论
非正交轨道
梯度
从头算
valence bond theory, non-orthogonal orbitals, gradient, ab initio