A theoretical study of semiclassic models: Toward a quantum mechanical representation of chemical processes

CASPT2 level of theory and aug‐cc‐pV6Z atomic basis set for hydrogen and 6 base states is sufficient to accurately reproduce the historical calculations of Kolos‐Wolniewicz for H21Σ g+ potential energy curve. We found that for H + H process experimental and adiabatic theory results are contradictory. By analyzing different levels of semiclassic theory, we identify the nature of the failure. We propose an approximate scheme that may bridge semiclassic to QM model. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011