Molecular potential energy function and reaction dynamics for LaH 2 ( C 2V , X̃ 2 A 1 )

Abstract The present work has derived an analytical potential energy function for the ground state ( C 2 V , X 2 A 1 ) of LaH 2 . The electronic state and reasonable dissociation limits are correctly determined based on Atomic and Molecular Reaction Statics (AMRS), and then, using a relativistic compact effective potential (RCEP) for La. The equilibrium geometry, dissociation energy and harmonic frequencies for LaH 2 have been calculated by ab initio methods. The results show that R (LaH)=2.1945 A, ∠HLaH=124.4° and D e (LaH 2 )=5.599 eV, and ν 1 , ν 2 and ν 3 are 1216.521, 1087.417 and 2156.957 cm −1 , respectively. Molecular reaction dynamics for the collision La( 2 D g ) + H 2 ( X 1 Σ g + , v=j=0) has been studied based on the analytical potential energy function of LaH 2 (X 2 A 1 ) by using the Monte Carlo quasi-classical trajectory approach. The results for the collision process indicate that the main channel is the exchange reaction La( 2 D g ) + H 2 ( X 1 Σ g + , v=j=0)→ LaH ( X 1 Σ + , v′,j′)+ H( 2 S g ) with the product LaH, and without the formation of the complex compound LaH 2 . The relationship of the reactive cross-section σ r with the relative translational energy E t shows that there is a threshold energy of 40 kcal/mol. Because of the tremendous difference in the masses of La and H 2 , these is a direct collision, and the distributions of the products LaH and H 2 are along the direction of forward scattering.