Effect of locality of exchange-correlation potential for excited state calculation

Abstract

Density functional theory (DFT) is the most widely used method of calculating the electronic structure of molecules and solids. Thanks to the advance of the exchange-correlation energy functional, now the DFT becomes a useful tool for the material and molecular design. One of the most important improvements in DFT would be the adopting the exact-exchange energy obtained from the Hartree-Fock method, so-called hybrid functional. For the DFT calculation, exchange-correlation potential should be constructed from the density information and exchange-correlation functional. Unlike the conventional DFT, it is possible to make two different types of exchange-correlation potential for hybrid functionals. The standard way employs the non-local Hartree-Fock operator. Alternatively, one can use the local multiplicative exact-exchange potential, which can be made from the optimized effective potential method. Both approaches provide similar results for the ground state calculations. On the other hands, the excited state related properties such as characteristics virtual orbitals are quite different. In this talk, I will introduce the difference between two types of exchange-correlation potentials and will show you that the virtual orbitals obtained from local exchange-correlation potential are better for the excited state calculation.