Zero-point energy vibrational configuration interaction

The formation of PH4 from PH3 and H in low-temperature matrices upon y irradiation is described in Section 1.4.1, p. 312. An ab initio MO calculation at the UHF/4-31G level predicted that PH3 and H individually are energetically more favorable than PH4 by 135 kJ/mol [15] see also Section 1.4.1, p. 313. The differences between the total energies of the reactants and the products for the formation of PHg from PH3 and H2 (+188 kJ/mol) or 2H (-246 kJ/mol) were obtained from ab initio MO calculations including configuration interactions but neglecting the differences in zero-point vibrational energies [16] see also Chapter 1.5, p. 321. 

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