TY - JOUR

T1 - Evaluation of first- and second-order nonadiabatic coupling elements from large multiconfigurational self-consistent-field wave functions

AU - Ågren, H.

AU - Flores-Riveros, A.

AU - Jensen, H. J.Aa

PY - 1986/1/1

Y1 - 1986/1/1

N2 - An efficient method is proposed for evaluating first- and second-order nonadiabatic matrix elements of the form i(q;Q)j(q;Q)/Q and i(q;Q)2j(q;Q)/Q2, where i(q;Q) and j(q;Q) denote multiconfigurational self-consistent-field electron wave functions. The method is based on a finite-difference procedure and requires the numerical computation of symmetric overlaps of the type i(q,Q0-x)j(q,Q0 +x). It gives an accuracy which is quadratic in the nuclear displacement x for both the first- and second-order nonadiabatic coupling constants. The wave functions are separately optimized for each state and obtained through the direct second-order MCSCF method. The biorthogonal scheme of Malmquist is implemented that expresses i(q;Q) and j(q:Q) in an orthogonal common basis. The method is applied for the calculation of the nonadiabatic coupling elements and the Born-Oppenheimer corrections to the two lowest +2 states of NaLi+, relevant for analyzing the asymmetric charge exchange in the ion-atom collision Na+Li+Na++Li.. AE.

AB - An efficient method is proposed for evaluating first- and second-order nonadiabatic matrix elements of the form i(q;Q)j(q;Q)/Q and i(q;Q)2j(q;Q)/Q2, where i(q;Q) and j(q;Q) denote multiconfigurational self-consistent-field electron wave functions. The method is based on a finite-difference procedure and requires the numerical computation of symmetric overlaps of the type i(q,Q0-x)j(q,Q0 +x). It gives an accuracy which is quadratic in the nuclear displacement x for both the first- and second-order nonadiabatic coupling constants. The wave functions are separately optimized for each state and obtained through the direct second-order MCSCF method. The biorthogonal scheme of Malmquist is implemented that expresses i(q;Q) and j(q:Q) in an orthogonal common basis. The method is applied for the calculation of the nonadiabatic coupling elements and the Born-Oppenheimer corrections to the two lowest +2 states of NaLi+, relevant for analyzing the asymmetric charge exchange in the ion-atom collision Na+Li+Na++Li.. AE.

UR - http://www.scopus.com/inward/record.url?scp=33645454708&partnerID=8YFLogxK

U2 - 10.1103/PhysRevA.34.4606

DO - 10.1103/PhysRevA.34.4606

M3 - Journal article

AN - SCOPUS:33645454708

VL - 34

SP - 4606

EP - 4614

JO - Physical Review A (Atomic, Molecular and Optical Physics)

JF - Physical Review A (Atomic, Molecular and Optical Physics)

SN - 2469-9926

IS - 6

ER -