Nonempirical LCAO–MO–SCF Study of the Energy Surface for Linear HeH2+

Abstract

The nonempirical LCAO–SCF–MO method using a contracted Gaussian basis is used to generate a potential energy surface for the ground state of the linear HeH2+ system. Recently, Chupka, Berkowitz, and Russell reported that even above threshold the cross sections for the reaction H2++He=HeH++H, are strongly dependent on the vibrational state of the H2+ ion. Examination of the calculated potential-energy surface for this reaction reveals that the energy barrier for this reaction occurs very late in the exit channel. This result, coupled with the work of Polanyi and Wong on the effect of the position of the potential-energy barrier, suggests that this late energy barrier is the reason that vibrational energy is much more effective than translational energy in causing this reaction. Another interesting feature of the calculated potential energy surface is the presence of a minimum corresponding to a HeH2+ complex. Investigation of the energy of this complex as a function of He–H–H bond angle demonstrates that the 180° form is the most stable.