A density matrix functional with occupation number driven treatment of dynamical and nondynamical correlation.
A density matrix functional with occupation number driven treatment of dynamical and nondynamical correlation.
复制标题
密度矩阵函数与占用数驱动的动态和非动态相关性处理。
DOI：
10.1063/1.2998201
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
E. Baerends
中科院分区：
文献类型：
--
作者：
Daniel R. Rohr;K. Pernal;O. Gritsenko;E. Baerends
最近提出的一系列修正的最早的JK唯一的泛函，大大提高了密度矩阵泛函理论（DMFT）的前景。尽管如此，这些泛函中最先进的（修正C3）需要预先选择电子对密度Gamma（r（1），r（2））中涉及属于电子对键的成键和反键自然轨道（NO）的项。理想情况下，DMFT功能应该只依赖于NO和他们的占领数，我们提出了一个功能与占领数驱动的对密度项的权重。这些被制定为“阻尼”的某些范围内的占领数的两个电子累积量，出现在扩展的两个粒子的密度矩阵的范例两个电子系统。C3的这个自动版本，我们记为AC3，提供了电子对键的正确解离极限，并且它很好地再现了多参考组态相互作用（MRCI）方法在十电子取代CH（4），NH（3），H（2）O和HF系列中电子对键解离的势能曲线。AC3精确地再现了实验平衡距离，在R（e）处，它产生了十电子系统的相关能，与MRCI值相比，绝对值的平均误差仅为3.3%。我们强调的重要性，治疗强相关的情况下（NO职业人数显着不同，从2.0和0.0）的累积适当的条款。
A recently proposed series of corrections to the earliest JK-only functionals has considerably improved the prospects of density matrix functional theory (DMFT). Still, the most advanced of these functionals (correction C3) requires a preselection of the terms in the pair density Gamma(r(1),r(2)) involving the bonding and antibonding natural orbitals (NOs) belonging to an electron pair bond. Ideally, a DMFT functional should only depend on the NOs and their occupation numbers, and we propose a functional with an occupation number driven weighing of terms in the pair density. These are formulated as "damping" for certain ranges of occupation numbers of the two-electron cumulant that arises in the expansion of the two-particle density matrix of the paradigmatic two-electron system. This automatic version of C3, which we denote AC3, provides the correct dissociation limit for electron pair bonds and it excellently reproduces the potential energy curves of the multireference configuration interaction (MRCI) method for the dissociation of the electron pair bond in the series of the ten-electron hydrides CH(4), NH(3), H(2)O, and HF. AC3 reproduces closely the experimental equilibrium distances and at R(e) it yields correlation energies of the ten-electron systems with an average error in the absolute values of only 3.3% compared to the MRCI values. We stress the importance of treatment of strong correlation cases (NO occupation numbers differing significantly from 2.0 and 0.0) by appropriate terms in the cumulant.