Simulating the HeI photoelectron spectrum of Cl2O with new full-dimensional adiabatic potential energy surfaces of Cl2O(X̃1A1), Cl2O+(X̃2B1), and Cl2O+(C̃2A2) and a three-state diabatic potential energy matrix of Cl2O+(Ã2B2, B̃2A1, and 22A1): a quantum mechanical study

Abstract

To interpret the HeI photoelectron spectrum of Cl₂O (involving four lowest electronic states of Cl₂O⁺), in this work we first constructed the associated adiabatic full-dimensional potential energy surfaces (PESs) of Cl₂O(X̃¹A₁), Cl₂O⁺(X̃²B₁), and Cl₂O⁺(C̃²A₂) and a diabatic potential energy matrix (PEM) of Cl₂O⁺(A^̃2B₂, B̃²A₁, and 2²A₁) using the explicitly correlated internally contracted multi-reference configurational interaction with Davidson correction (MRCI-F12+Q) and neural network methods. Particularly for the A^̃2B₂, B̃²A₁, and 2²A₁ states of Cl₂O⁺ coupled in terms of conical intersection, their diabatization is achieved by the neural network approach based merely on the associated adiabatic energies. With the help of newly constructed adiabatic PESs and the diabatic PEM, the HeI photoelectron spectrum of Cl₂O is further computed quantum mechanically. The calculated photoelectron spectrum is found to be in good accord with experiment. The mode specificity in the HeI photoelectron bands of Cl₂O is analyzed in detail.