COUPLED-CLUSTER THEORY EMPLOYING APPROXIMATE INTEGRALS : AN APPROACH TO AVOID THE INPUT/OUTPUT AND STORAGE BOTTLENECKS
COUPLED-CLUSTER THEORY EMPLOYING APPROXIMATE INTEGRALS : AN APPROACH TO AVOID THE INPUT/OUTPUT AND STORAGE BOTTLENECKS
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采用近似积分的耦合簇理论:避免输入/输出和存储瓶颈的方法
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
Timothy J. Lee
中科院分区：
文献类型：
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作者：
Alistair P. Rendell;Timothy J. Lee
通过在展开基中表示轨道乘积，某些类别的双电子积分被近似用于CCSD（T）计算（单和双耦合簇加上连接三重激发效应的微扰估计）。这导致磁盘存储和输入/输出需求的大幅减少，而计算工作量通常只有适度的增加。新的程序将允许进行非常大的CCSD（T）计算，仅受可用处理器时间的限制。使用的分子基础作为扩展的基础上，明确的数值比较的平衡几何形状，谐波频率和能量差表明，由于使用近似积分的误差小于与截断的分子基组的误差。
By representing orbital products in an expansion basis, certain classes of two‐electron integrals are approximated for use in CCSD(T) calculations (singles and doubles coupled‐cluster plus a perturbational estimate of the effects of connected triple excitations). This leads to a very large reduction in disk storage and input/output requirements, with usually only a modest increase in computational effort. The new procedure will allow very large CCSD(T) calculations to be undertaken, limited only by available processor time. Using the molecular basis as the expansion basis, explicit numerical comparisons of equilibrium geometries, harmonic frequencies, and energy differences indicate that the error due to the use of approximate integrals is less than the error associated with truncation of the molecular basis set.