Dynamics of (H−,H2) collisions: A time-dependent quantum mechanical investigation on a new ab initio potential energy surface

Abstract

A global analytical potential energy surface for the ground state of H(3)(-) has been constructed by fitting an analytic function to the ab initio potential energy values computed using coupled cluster singles and doubles with perturbative triples [CCSD(T)] method and Dunning's augmented correlation consistent polarized valence triple zeta basis set. Using this potential energy surface, time-dependent quantum mechanical wave packet calculations were carried out to calculate the reaction probabilities (P(R)) for the exchange reaction H(-)+H(2)(v, j)-->H(2)+H(-), for different initial vibrational (v) and rotational (j) states of H(2), for total angular momentum equal to zero. With increase in v, the number of oscillations in the P(R)(E) plot increases and the oscillations become more pronounced. While P(R) increases with increase in rotational excitation from j=0 to 1, it decreases with further increase in j to 2 over a wide range of energies. In addition, rotational excitation quenches the oscillations in P(R)(E) plots.

Time Dependent Wave Packet Study of the H<sup>-</sup>+ H<sub>2</sub> Nonreactive Scattering

“…The ion-molecule reactions are of interest in understanding the collision processes in interstellar media, the plasma, and high-energy physic studies [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. However, there have been a number of experimental and theoretical studies on the reaction cross sections of H − + H 2 reactions and its isotopic variants [10][11][12][13][14][15][16].…”

“…Gianturco and Kumar [20] calculated the differential and integral cross sections for vibrationally in elastic processes in (H -,H 2 ) collisions over collision energy (107.69-922.4 kcal/mol) on SM PES. Recently, Panda and Sathyamurthy [21] have computed an ab initio PES of 3 H  systems using coupled cluster singles and doubles with nonperturbative triples method for a wide range of geometries. Subsequently, there are many theoretical studies about the title reactions using this global ab initio potential energy surface (PES) [10,21,22].…”

“…Recently, Panda and Sathyamurthy [21] have computed an ab initio PES of 3 H  systems using coupled cluster singles and doubles with nonperturbative triples method for a wide range of geometries. Subsequently, there are many theoretical studies about the title reactions using this global ab initio potential energy surface (PES) [10,21,22]. The pioneer work by Michels and Paulson [15] reported the biggest theoretical value of the cross section of this system (i.e, 2.5 Angs squared).…”

“…Recently, using ab initio PES of Ref. 21 and time-dependent wave-packet quantum method, Yao et al [10] calculated the cross sections for both the reaction D − + H 2 and the reaction H − + D 2 in the collision energy range of 0.2 -2.4 eV. Their calculations showed that the Coriolis coupled method was more consistent with the experimental ones than the centrifugal sudden approximation, and a pronounced isotopic effect was also observed to compare the two reactive systems in their previous report [10].…”

“…The pioneer work by Michels and Paulson [15] reported the biggest theoretical value of the cross section of this system (i.e, 2.5 Angs squared). Panda and Sathyamurthy [21] used the time dependent quantum mechanics method within the centrifugal sudden approximation for computing the integral reaction cross section values for H − + H 2 reaction (υ = 0,  j = 0) and its isotopic variants. Their results were also found to be in good agreement with the experimental results of Muller et al [17] but larger than those of Haufler et al [18].…”