Active-Space N-Representability Constraints for Variational Two-Particle Reduced Density Matrix Calculations

作者：Shenvi Neil^*; Izmaylov Artur F

来源：Physical Review Letters, 2010, 105(21): 213003.

DOI：10.1103/PhysRevLett.105.213003

The ground-state energy of a system of fermions can be calculated by minimizing a linear functional of the two-particle reduced density matrix (2-RDM) if an accurate set of N-representability conditions is applied. In this Letter we introduce a class of linear N-representability conditions based on exact calculations on a reduced active space. Unlike wave-function-based approaches, the 2-RDM methodology allows us to combine information from calculations on different active spaces. By adding active-space constraints, we can iteratively improve our estimate for the ground-state energy. Applying our methodology to a 1D Hubbard model yields a significant improvement over traditional 2-positivity constraints with the same computational scaling.

• 出版日期2010-11-18