Regularized vibrational energies prediction and potential energy function study for some interhalogen diatomic molecules

Full vibrational energies and corresponding analytical potential energy functions (APEFs) for A′2(3Π) of ClF, X1Σ+ of ICl, X1Σ+ of IBr, and X1Σ+of IF are obtained by four-term variational algebraic energy-consistent method [VAECM(4)]. Three major methods are used to handle the regularization problems and make the results more reliable: (1) physical constraints like progressive dissociation behavior are used to overcome overfitting problems; (2) reasonable variational method is used to expand the experimental dataset and make the model optimization much faster; and (3) validation dataset is used to further enhance the reliability. After these treatments, our results agree well with experiment and have a good physical converged behavior in molecular dissociation and asymptotic region. This study provides important reference data for the related molecules.