Quantum Chemical Methods Based on Electron-Charge Screening

Abstract

In order to accurately predict the chemical properties of large molecular systems without drastically increasing the computational cost, one can model electrons as quasi-particles (bare electrons with a screening potential around them). By accounting for this screening in Schr¨odinger’s equation with either a correlation factor of the wave function or an effective Hamiltonian, one can determine a screening parameter for a given system. Then, by optimizing screening parameters for different systems, one can develop a functional relationship for these parameters and use it to improve traditional Hartree-Fock and density functional theory methods to obtain more accurate results, with little increase in computational cost. In the two approaches considered, a variational approach and an effective Hamiltonian approach, there appears to be little correlation between the determined screening parameters from each approach. However, future investigation of the variational and effective Hamiltonian approaches with other correlation factors and other screening potentials, respectively, may produce better results.