Diffusion Monte Carlo Study of Bond Dissociation Energies for BH2, B(OH)2, BCl2, and BCl

On basis of bond dissociation energies (BDEs) for BH2, B(OH)(2), BCl2, and BCl, the diffusion Monte Carlo (DMC) method is applied to explore the BDEs of HB-H, HOB-OH, ClB-Cl, and B-Cl. The effect of the choice of orbitals, as well as the backflow transformation, is studied. The Slater-Jastrow DMC algorithm gives BDEs of 359.1 +/- 0.12 kJ/mol for HB-H, 410.5 +/- 0.50 kJ/mol for HOB-OH, 357.8 +/- 1.46 kJ/mol for ClB-Cl, and 504.5 +/- 0.96 kj/mol for B-Cl using B3PW91 orbitals and similar BDEs when B3LYP orbitals are used. DMC with backfiow corrections (BF-DMC) gives a HB-H BDE of 369.9 +/- 0.12 kJ/mol which is close to one of the available experimental value (375.8 kJ/mol). In the case of HOB-OH BDE, the BF-DMC calculation is 446.0 +/- 1.84 kJ/mol that is closer to the experimental BDE. The BF-DMC BDE for ClB-Cl is 343.2 +/- 2.34 kJ/mol and the BF-DMC B-Cl BDE is 523.3 +/- 0.33 kJ/mol, which are close to the experimental BDEs, 341.9 and 530.0 kJ/mol, respectively.