Effctive nonadiabatic calculations on the ground state of the HD⁺ molecule

The nonadiabatic methodology, which is based on an effective elimination of the center‐of‐mass motion rather than explicit separation achieved by a coordinate transformation, is applied to the ground state of the HD⁺ molecule. The many‐body nonadiabatic wave function is generated in terms of explicitly correlated Gaussian functions. The analytical first and second derivatives of the variational functional with respect to the Gaussian exponents are applied in conjunction with the Newton–Raphson optimization method to find the nonadiabatic energy and the ground–wave function. The numerical results are compared with conventional nonadiabatic calculations. © 1995 John Wiley & Sons, Inc.