Spin-orbit coupled potential energy surfaces and properties using effective relativistic coupling by asymptotic representation

Abstract

A new method has been reported recently [H. Ndome, R. Welsch, and W. Eisfeld, J. Chem. Phys. 136, 034103 (2012)] that allows the efficient generation of fully coupled potential energy surfaces (PESs) including derivative and spin-orbit (SO) coupling. The method is based on the diabatic asymptotic representation of the molecular fine structure states and an effective relativistic coupling operator and therefore is called effective relativistic coupling by asymptotic representation (ERCAR). The resulting diabatic spin-orbit coupling matrix is constant and the geometry dependence of the coupling between the eigenstates is accounted for by the diabatization. This approach allows to generate an analytical model for the fully coupled PESs without performing any ab initio SO calculations (except perhaps for the atoms) and thus is very efficient. In the present work, we study the performance of this new method for the example of hydrogen iodide as a well-established test case. Details of the diabatization and the accuracy of the results are investigated in comparison to reference ab initio calculations. The energies of the adiabatic fine structure states are reproduced in excellent agreement with reference ab initio data. It is shown that the accuracy of the ERCAR approach mainly depends on the quality of the underlying ab initio data. This is also the case for dissociation and vibrational level energies, which are influenced by the SO coupling. A method is presented how one-electron operators and the corresponding properties can be evaluated in the framework of the ERCAR approach. This allows the computation of dipole and transition moments of the fine structure states in good agreement with ab initio data. The new method is shown to be very promising for the construction of fully coupled PESs for more complex polyatomic systems to be used in quantum dynamics studies.

Information theoretic measures for quantifying sequence–ensemble relationships of intrinsically disordered proteins

“…All-atom Monte Carlo simulations were performed using the ABSINTH implicit solvent model and forcefield paradigm as made available in version 2.0 CAMPARI simulation package ( ) ( Vitalis and Pappu, 2009a , b ; Radhakrishnan et al , 2012 ). Simulations were based on the abs_3.2_opls.prm parameter set in conjunction with optimized parameters for neutralizing and excess Na + and Cl – ions ( Mao and Pappu, 2012 ). Simulations were performed using a spherical droplet with a diameter of 285 Å with explicit ions to mimic a concentration of 10 mM NaCl.…”

Revisiting the (E + A) ⊗ (e + a) problems of polyatomic systems with trigonal symmetry: general expansions of their vibronic Hamiltonians

“…48,49 The spin-orbit interaction can couple states of different symmetries and spins; there is an intricate interplay between SOC and the JT (and pJT) effects. [50][51][52][53][54][55][56][57][58][59][60][61][62] The SOC operator should hence be included in the vibronic Hamiltonian expansion for those systems. Very recently, Domcke et al 38 derived the relations between the SOC matrix elements and the electrostatic Hamiltonian elements for p orbitals.…”

General Formalism of Vibronic Hamiltonians for Tetrahedral and Octahedral Systems: Problems That Involve T, E States and t, e Vibrations

“…[52][53][54] The interplay between SOC and JT/pJT effects has been a long lasting research subject. [55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70] For JT/pJT systems with heavy nuclei, it is necessary to include the spin-orbit interaction in the vibronic Hamiltonian expansion. Very recently, Domcke et al 71 showed that there is a neat connection between the SOC and the electrostatic Hamiltonian matrix elements for a set of p Gaussian orbitals.…”