Journal of Physical Chemistry A, Vol.105, No.37, 8599-8603, 2001
The electronic spectrum of H2COH revisited
The electronic spectrum of the H2COH radical has been reinvestigated using the MRDCI method, an AO basis set containing two sets of s and p Rydberg functions, and diagonalized CI spaces on the order of 2.5 x 10(5). A detailed analysis of the calculations reveals that excitation energies obtained with truncated CI spaces overestimate the corresponding extrapolated and estimated full CI energies. The new results confirm the assignment made earlier by us on the basis of less extensive calculations: experimental T-0 values of 4.34 and 5.09 eV correspond to the excitations pi* --> 3p(x) and pi* --> 3p(z) respectively. As previously predicted, the pi* --> 3p(z) system has been shown experimentally to be polarized along the CO bond.