Local explicitly correlated second- and third-order Møller-Plesset perturbation theory with pair natural orbitals.
Local explicitly correlated second- and third-order Møller-Plesset perturbation theory with pair natural orbitals.
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DOI：
10.1063/1.4719981
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发表时间：
2011-08
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影响因子：
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通讯作者：
C. Hättig;D. Tew;Benjamin Helmich
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文献类型：
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作者：
C. Hättig;D. Tew;Benjamin Helmich
我们提出了一种算法，用于计算大分子基集极限附近显式相关的二阶和三阶Møller-Plesset能量，其成本形式为N(4)与系统大小N的比例。这是通过一种混合方法实现的，其中首先通过轨道特定虚拟（osv）利用局域性，然后通过对自然轨道（PNOs）利用局域性，并使用密度拟合近似积分。我们的方法结合了osv的低轨道转换成本和双振幅矢量的PNO表示的紧凑性。N(4)缩放不依赖于域的先验定义，对列表的强制截断，甚至筛选，并且能量平滑地收敛到用于选择PNO基的占用数阈值降低的规范值。对于MP2.5分子间相互作用能，我们发现使用8 -cc- pvtz基可以恢复99%的基准基集限制相关能贡献，并且平均只需要50个PNOs来关联显著轨道对。
We present an algorithm for computing explicitly correlated second- and third-order Møller-Plesset energies near the basis set limit for large molecules with a cost that scales formally as N(4) with system size N. This is achieved through a hybrid approach where locality is exploited first through orbital specific virtuals (OSVs) and subsequently through pair natural orbitals (PNOs) and integrals are approximated using density fitting. Our method combines the low orbital transformation costs of the OSVs with the compactness of the PNO representation of the doubles amplitude vector. The N(4) scaling does not rely upon the a priori definition of domains, enforced truncation of pair lists, or even screening and the energies converge smoothly to the canonical values with decreasing occupation number thresholds, used in the selection of the PNO basis. For MP2.5 intermolecular interaction energies, we find that 99% of benchmark basis set limit correlation energy contributions are recovered using an aug-cc-pVTZ basis and that on average only 50 PNOs are required to correlate the significant orbital pairs.