FERMI AND COULOMB HOLES OF MOLECULES IN EXCITED-STATES

Correlation holes of electrons with the same (Fermi hole) and different (Coulomb hole) spins in the ground (X(1) Sigma(+)), first (A(1) Sigma(+)) and second (B-1 Pi) excited states of UH were constructed from full configuration interaction (CI) wave functions. It was found that the shapes of both the Fermi and Coulomb holes in these states are dependent on the location of the reference electron. When the reference electron is chosen to be close to the Li nucleus, the Fermi correlation results in a large negative hole for all three states. However, the A(1) Sigma(+) excited state is further characterized by displaying a second hole around the H nucleus, and in the B-1 Pi state, the hole is elongated along the molecular axis. Coulomb correlation shows up strongly in the A(1) Sigma(+) state and, in addition, there is clearly correlation of electrons at the two nuclei. These features of the correlation holes were compared with those from a two-Slater-determinant model wave function. The Hartree, Fermi, and Coulomb screening potentials in these states were also studied in the light of possible modeling of the correlation functionals for the excited states. (C) 1995 John Wiley & Sons, Inc.