## A new potential energy surface for H[sub 2]Br and its use to calculate branching ratios and kinetic isotope effects for the H + HBr reaction

We have carried out multireference configuration interaction calculations with a large basis set for the H[sub 2]Br system at 104 geometries preselected for convenient use in fitting an analytic potential energy surface for the reactions H + HBr [yields] H[sub 2]Br and H + H[prime]Br [yields] H[prime] + HBr. The external part of the correlation energy is scaled (SEC method) to yield a 101 geometry data set which is fitted using the extended London -Eyring-Polanyi-Sato method with bond-distance- and internal-angle-dependent Sato parameters plus a three-center term localized at the colinear H-Br-H saddle point. The unweighted root-mean-square error for 88 pointsmore »