Global potential energy surfaces for the Al+(1S)+H2 system

Abstract

Global, three-dimensional multireference ab initio potential energy surfaces have been calculated for the AlH2+ system for the two lowest energy singlet states and the lowest energy triplet state. These surfaces were calculated using the multireference configuration interaction level of theory with a large basis set. The accuracy of the surfaces were checked against available experimental data and previous theoretical investigations. The areas of surface crossings between the ground state singlet surface and the lowest energy triplet surface and the first excited singlet surface have been thoroughly investigated in all three dimensions and found to give rise to two regions of surface crossings--an "early" crossing (reduced H2 distance) and a "late" crossing (enlarged H2 distance). It is anticipated that both of these crossings will be important in modeling the dynamics of the system. Each of the global potential energy surfaces were fit by interpolation methodology to obtain analytic representations of the surfaces. A representative classical simulation on the ground state singlet surface was performed and discussed.

The Al+–H2 cation complex: Rotationally resolved infrared spectrum, potential energy surface, and rovibrational calculations

“…10 Conversion of the Al + -H 2 complex to the inserted HAlH + form is predicted to proceed by breaking first the H 2 bond, followed by consecutive formation of two equivalent AlH bonds with a calculated activation energy of 85.0 kcal/ mol. 10 Related experimental 14 and theoretical [15][16][17][18] studies have focused on the Al + ͑ 1 S͒ +H 2 ͑ 1 ⌺ g + ͒ → AlH + ͑ 2 ⌺ + ͒ +H͑ 2 S͒ reaction which is 3.98 eV endothermic. 12,13 Although the insertion barrier is also predicted to be lowered for the larger Al + -͑H 2 ͒ n clusters, it remains appreciable ͑53.2 kcal/ mol for n =3͒.…”

Molecular Dynamics of Complex Gas-Phase Reactive Systems by Time-Dependent Groups

“…This difficulty is also being worked on by storing the group potential energy data to fast-access databases and combining these databases with accurate and computationally facile general methods of interpolation so that eventually the computationally expensive calculation of the ab initio intragroup interactions will yield to fast methods of interpolation. Interpolants similar to previous work − are being generalized for any dimensionality, and studies are being performed on methods of optimizing the interpolants so as to obtain general, accurate, and fast methods of PES interpolation.…”