Simulating the HeI photoelectron spectrum of Cl 2 O with new full-dimensional adiabatic potential energy surfaces of Cl 2 O(X̃ 1 A 1 ), Cl 2 O + (X̃ 2 B 1 ), and Cl 2 O + (C̃ 2 A 2 ) and a three-state diabatic potential energy matrix of Cl 2 O + (Ã 2 B 2 , B̃ 2 A 1 , and 2 2 A 1 ): a quantum mechanical study.

To interpret the HeI photoelectron spectrum of Cl 2 O (involving four lowest electronic states of Cl 2 O + ), in this work we first constructed the associated adiabatic full-dimensional potential energy surfaces (PESs) of Cl 2 O(X̃ 1 A 1 ), Cl 2 O + (X̃ 2 B 1 ), and Cl 2 O + (C̃ 2 A 2 ) and a diabatic potential energy matrix (PEM) of Cl 2 O + (A ̃2 B 2 , B̃ 2 A 1 , and 2 2 A 1 ) using the explicitly correlated internally contracted multi-reference configurational interaction with Davidson correction (MRCI-F12+Q) and neural network methods. Particularly for the A ̃2 B 2 , B̃ 2 A 1 , and 2 2 A 1 states of Cl 2 O + 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 Cl 2 O 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 Cl 2 O is analyzed in detail.