AB-INITIO CALCULATION OF THE ENERGY OF RECOMBINATIVE HYDROGEN DESORPTION FROM THE MONOHYDRIDE PHASE OF SI(100)

The quadratic CI (QCI) and density functional methods are used to calculate the strength of the Si-H bonds of the monohydride phase of the Si(100) 2 x 1 surface. The QCI and density functional calculations both indicate that the energy for removing the first H atom is 2-3 kcal/mol greater than that to remove the second H atom. In the QCI method the energies for removing the first and second H atoms are 83.1 and 79.8 kcal/mol, respectively. The corresponding energies obtained from density functional calculations with nonlocal corrections are 79.4 and 77.6 kcal/mol. The QCI and density functional methods give H-2 desorption energies of 62.1 and 51.7 kcal/mol, respectively. About half of the difference in the latter two reaction energies is due to the different binding energies of H-2 in the two methods.