Highly accurate excited-state energies from direct computation of the 2-electron reduced density matrix by the anti-Hermitian contracted Schrodinger equation

作者：Sturm Erica J; Mazziotti David A^*

来源：Molecular Physics, 2016, 114(3-4): 335-343.

DOI：10.1080/00268976.2015.1074739

• Reduced density matrices
• electron correlation
• excited states

Directly solving for the 2-electron reduced density matrix (2-RDM) via the anti-Hermitian contracted Schrodinger equation (ACSE) enables computations for excited states energies without the N-electron wave function. Of particular interest are excitations and dissociation curves that exhibit strong multi-reference correlation effects. The ground and excited states of the molecules HF, H2O, and N-2 are examined at both equilibrium and non-equilibrium geometries to compare the ability of the ACSE and widely used ab initio techniques to treat strong multi-reference electron correlation. Calculations are performed with double-zeta basis sets for calibration with full configuration interaction (FCI). Multi-reference second-order perturbation theory (MRPT2) and the ACSE both provide qualitative precision with respect to FCI data, although the ACSE's capability to include higher order correlation effects permits near-FCI accuracy for ground and excited states and excitation energies.

• 出版日期2016-2-16