Chemical Physics Letters, Vol.366, No.3-4, 321-328, 2002
CAS-DFT based on odd-electron density and radical density
We here propose new schemes of complete active space-density functional theory (CAS-DFT). It is based on the idea that the previous odd-electron density and radical density are used to express the spin-polarizability of CAS wave-functions. We have applied these schemes to optimize geometries and to calculate the singlet-triplet energy gaps of several molecules and compare the results with those by the other methods and experiment. It was found that our schemes based on radical density give excellent results although our schemes drastically reduce the computational cost. (C) 2002 Elsevier Science B.V. All rights reserved.