In part I, of this series, a ring contraction model was proposed as the basic mechanism of slow crack growth in silica glass. AM1 molecular orbital theory running on a CAChe workstation was used to find the transition state for the contraction of a 4-fold ring into a 3-fold ring. Using the same AM1 method, the predicted transition state has been found for the contraction of a 5-fold ring into a 4-fold ring. The activation barrier to fracture for this contraction is E(f) = + 7.9 Kcal mol(-1) using Unrestricted Hartree Fock(UHF) theory. As would be expected, the barrier calculated for Restricted Hartree Fock (RHF) was a little higher at E(f) = + 14.8 Kcal mol(-1). This confirms our initial hypothesis that ring contraction can lead to much lower fracture energies than expected from simple Si-O bond breaking. Several different schemes of ring contractions are possible for both 5-fold and 6-fold ring structures. All contraction paths have different intermediate structures that lead to the same end point of slow crack growth. The various barriers to fracture range from + 8 to + 52 Kcal mol(-1) for the 5-fold ring contractions and from + 9 to + 41 Kcal mol(-1) for 6-fold ring contractions.