Communication: The distinguishable cluster approximation

摘要: We present a method that accurately describes strongly correlated states and captures dynamical correlation. It is derived as modification of coupled-cluster theory with single double excitations (CCSD) through consideration particle distinguishability between dissociated fragments, whilst retaining the key desirable properties particle-hole symmetry, size extensivity, invariance to rotations within occupied virtual spaces, exactness for two-electron subsystems. The resulting method, called distinguishable cluster approximation, smoothly dissociates difficult cases such nitrogen molecule, modest N(6) computational cost CCSD. Even molecules near their equilibrium geometries, new model outperforms also massively encountered when dissociating hydrogen lattices, proxy metal-insulator transition, fully system treated exactly.