A configuration interaction study of the spin dipole‐dipole parameters for formaldehyde and methylene

Abstract

Abstract The electron spin dipole‐dipole contribution to the zero field splitting has been evaluated for the 3 A 2 ( n → π*) and 3 A 1 (π → π*) states of formaldehyde using a CI wave function constructed from contracted Gaussian‐lobe functions. The values D = 0.539 cm −1 and E = 0.031 cm −1 were obtained for the 3 A 2 ( n → π*) state and D = −0.588 cm −1 and E = 0.058 cm −1 were obtained for the 3 A 1 (π → π*) state using the CI wave function constructed from SCF orbitals of the respective parent configurations. An analysis of the effect of CI on the parameters is given for the 3 A 2 ( n n → π*) state of formaldehyde and the 3 B 1 ground state of methylene. Numerical results are given which show that internally consistent self‐consistent field orbitals ( ICSCF ) are superior to canonical SCF orbitals as a starting point for a CI calculation. Our CI wave function for the 1 A 1 ground state gave an energy of −114.13658 hartrees which is significantly lower than any previously reported energy calculation. This wave function gives a dipole moment of 2.22 Debye (C + O − ) in good agreement with the experimental value of 2.33 ± 0.02 Debye.