Author/Authors :
Cramer، نويسنده , , Christopher J. and Dulles، نويسنده , , Frederic J. and Giesen، نويسنده , , David J. and Almlِf، نويسنده , , Jan، نويسنده ,
Abstract :
A spin-annihilation technique for a single determinant formed from Kohn-Sham orbitals is described for the calculation of excited state singlet energies. This procedure accurately calculates the 1 1Bu ← 1 1Ag vertical transition for s-trans-1,3-butadiene using the Becke-Lee-Yang Parr (BLYP) functional. For this system, extrapolating from triplet and 50:50 Bu state energies gives poor results at either the UHF or BLYP levels; spin-annihilated Hartree-Fock theory is similarly unsuccessful.
