Executive Summary : | The aim of this project is to develop low-cost four-component relativistic coupled cluster methods based on natural spinors. The frozen natural spinor framework provided a compact description of the virtual space for wave-function based calculations. Truncating the virtual space in the frozen natural spinor framework can lead to a major speedup of the relativistic coupled cluster calculations without any significant loss of accuracy. Natural spinors can be obtained by diagonalizing the correlated one-particle reduced density generated from the relativistic MP2 calculations. PIs propose to develop relativistic coupled cluster methods based on frozen natural spinors for energy and property calculation for the ground and excited states of molecules containing heavy elements. The newly developed relativistic quantum chemistry methods will be made freely available as a part of an Indian quantum chemistry software package. |