Hapka Michał, Pastorczak Ewa, Krzemińska Agnieszka, Pernal Katarzyna
Institute of Physics, Lodz University of Technology, ul. Wolczanska 219, 90-924 Lodz, Poland.
J Chem Phys. 2020 Mar 7;152(9):094102. doi: 10.1063/1.5138980.
We propose a multiconfiguration density functional combining a short-range density functional approximation with a novel long-range correction for dynamic correlation effects. The correction is derived from the adiabatic connection formalism so that the resulting functional requires access only to one- and two-electron reduced density matrices of the system. In practice, the functional is formulated for wavefunctions of the complete active space (CAS) type and the short-range density functional part is made dependent on the on-top pair density via auxiliary spin densities. The latter allows for reducing the self-interaction and the static correlation errors without breaking the spin symmetry. We study the properties and the performance of the non-self-consistent variant of the method, termed lrAC0-postCAS. Numerical demonstration on a set of dissociation energy curves and excitation energies shows that lrAC0-postCAS provides accuracy comparable with more computationally expensive ab initio rivals.
我们提出了一种多组态密度泛函，它将短程密度泛函近似与一种用于动态相关效应的新型长程校正相结合。该校正源自绝热连接形式，因此所得泛函仅需访问系统的单电子和双电子约化密度矩阵。在实际应用中，该泛函是针对完全活性空间（CAS）类型的波函数制定的，并且短程密度泛函部分通过辅助自旋密度依赖于顶对密度。后者允许在不破坏自旋对称性的情况下减少自相互作用和静态相关误差。我们研究了该方法的非自洽变体lrAC0-postCAS的性质和性能。在一组解离能曲线和激发能上的数值演示表明，lrAC0-postCAS提供的精度与计算成本更高的从头算竞争对手相当。
