Beyond Born-Oppenheimer theory for ab initio constructed diabatic potential energy surfaces of singlet H3+ to study reaction dynamics using coupled 3D time-dependent wave-packet approach

Abstract

The workability of beyond Born-Oppenheimer theory to construct diabatic potential energy surfaces (PESs) of a charge transfer atom-diatom collision process has been explored by performing scattering calculations to extract accurate integral cross sections (ICSs) and rate constants for comparison with most recent experimental quantities. We calculate non-adiabatic coupling terms among the lowest three singlet states of H system (1A, 2A, and 3A) using MRCI level of calculation and solve the adiabatic-diabatic transformation equation to formulate the diabatic Hamiltonian matrix of the same process [S. Mukherjee et al., J. Chem. Phys. 141, 204306 (2014)] for the entire region of nuclear configuration space. The nonadiabatic effects in the D + H reaction has been studied by implementing the coupled 3D time-dependent wave packet formalism in hyperspherical coordinates [S. Adhikari and A. J. C. Varandas, Comput. Phys. Commun. 184, 270 (2013)] with zero and non-zero total angular momentum (J) on such newly constructed accurate (ab initio) diabatic PESs of H. We have depicted the convergence profiles of reaction probabilities for the reactive non-charge transfer, non-reactive charge transfer, and reactive charge transfer processes for different collisional energies with respect to the helicity (K) and total angular momentum (J) quantum numbers. Finally, total and state-to-state ICSs are calculated as a function of collision energy for the initial rovibrational state (v = 0, j = 0) of the H molecule, and consequently, those quantities are compared with previous theoretical and experimental results.

Charge transfer ionic character illustration for strontium hydride ion through a diabatic investigation

“…We hope this complete set of data can be useful for further studies such as calculating the non‐adiabatic couplings terms (NACTs) which play a crucial role in non‐adiabatic process.…”

$$\hbox {H}^{+} + \hbox {O}_2$$ H + + O 2 system revisited: four-state quasidiabatic potential energy surfaces and coupling potentials

“…However, it must be noted that the topology of quasidiabatic PESs and their potential couplings could be sensitive to the accuracy achieved in the computations. It is also worth mentioning here that adiabatic and quasidiabatic PESs for the H + 3 have also been obtained recently 49,50 for the lowest three singlet electronic states in the hyper spherical coordinates by computing nonadiabatic coupling matrix elements (NACME) and by satisfying the curl condition and solving the adiabatic-to-diabatic equation, followed by the coupled three-dimensional time-dependent wave packet studies.…”

Time-dependent quantum mechanical wave packet dynamics

“…125,126 As mentioned earlier, one way to avoid the channel-dependent Jacobi coordinates is to work in hyperspherical coordinates. The number of papers published using hyperspherical coordinates in the TDSE framework is rather limited [127][128][129][130][131] because of the difficulty in the final state analysis. Another practical aspect of the TDQMWP approach (applicable to the TIQM approach as well) is the number of J values for which the calculations have to be repeated.…”

“…More experimental and theoretical work are necessary to resolve this mystery. 322 Some of the other systems that have been investigated using the TDQMWP method including non-adiabatic coupling are: (H + , H 2 ), 128,285,286 (F, H 2 ), 277,323 (Cl, H 2 ), 32,279,324 (Br, H 2 ), 325 (O, H 2 ), 274,326 and more recently (F, CH 4 ). 287…”