An empirical potential-energy surface for the He–I2(BΠu3) van der Waals complex including three-body effects

Abstract

An empirical intermolecular potential surface is proposed for the He-I 2 ͑B 3 ⌸ u ͒ complex, modeled as a sum of pairwise He-I Morse interactions plus a three-body interaction term. The potential reproduces with very good agreement the spectral blueshifts and vibrational predissociation lifetimes measured for He-I 2 ͑B , Ј͒ in the range Ј= 10-67 of I 2 vibrational excitations. In particular, the accuracy achieved in the description of the experimental data for high Ј levels is attributed to the three-body interaction term included in the potential. The behavior of the potential surface with the I-I separation is analyzed and correlated with the experimental findings.

Ab initio vibrational predissociation dynamics of He–I2(B) complex

“…The HeI 2 ͑B͒ UCCSD͑T͒ surface 27 has been also found reasonably consistent with different empirical potentials. 30,31 In this paper, we use the above mentioned X and B ab initio PESs to calculate energies and lifetimes of the predissociating HeI 2 for T-shaped and linear isomers, respectively. As it can be seen the agreement has become very good with the latest experimental determinations.…”

Effect of the Intermolecular Excitation in the Vibrational Predissociation Dynamics of van der Waals Complexes and the Implications for Control

“…For the B electronic state of the complexes, the interaction potential surface is represented as V ( r , R , θ ) = V X 2 ( r ) + V int ( r , R , θ ) where the V X 2 ( r ) term represents the intramolecular potential of the isolated X 2 molecule in the B electronic state, and V int ( r , R , θ) is the intermolecular potential, typically represented by a sum of pairwise Rg–X interactions. The specific functional forms for the above two terms have been reported previously for Ne–Cl 2 ( B ), Ne–Br 2 ( B ) (refs and for the Ne–Br 2 intermolecular potential and for the V Br 2 ( r ) term, respectively), Ne–I 2 ( B ), and He–I 2 ( B ) . The above interaction potentials are empirical ones.…”

“…The above interaction potentials are empirical ones. It is noted that the He–I 2 ( B ) intermolecular potential includes three-body effects.…”

“…The specific functional forms for the above two terms have been reported previously for Ne−Cl 2 (B), 43 Ne−Br 2 (B) (refs 23 and 44 for the Ne−Br 2 intermolecular potential and for the V Br 2 (r) term, respectively), Ne−I 2 (B), 45 and He−I 2 (B). 46 The above interaction potentials are empirical ones. It is noted that the He−I 2 (B) intermolecular potential 46 includes three-body effects.…”

The role of orbiting resonances in the vibrational relaxation of I2(B,v′ = 21) by collisions with He at very low energies: a theoretical and experimental study

“…The system is represented in Jacobi coordinates (r,R,y), where r is the I-I internuclear distance, R is the separation between He and the I 2 center-of-mass, and y is the angle between the vectors associated with r and R. The potential-energy surface used to model the interaction between I 2 (B) and He along the collision is an empirical potential developed to represent the I 2 (B) À He vdW complex, which has been described in detail elsewhere. 44 This surface was modeled as a sum of pairwise I-He Morse interaction plus a three-body interaction term involving an explicit dependence on the I-I internuclear separation. The parameters of the potential surface were fitted in order to reproduce the available spectroscopic and dynamical experimental data (spectral blueshifts and vibrational predissociation lifetimes) in a wide range, v 0 = 10-67, of vibrational excitations of I 2 (B,v 0 ) À He.…”