Non-adiabatic coupling, two-state molecular

HCCS radical, Renner-Teller effect, tetraatomic molecules, II electronic states, 633-640 H2D molecule, non-adiabatic coupling, two-state molecular system, 107-109 HD2 molecule, permutational symmetry isotopomers, 713-717 potential energy surfaces, 692-694 Heaviside function ... 

Mixing angle, non-adiabatic coupling, two-state molecular system, H3 molecule, 104— 109... 

Neumann boundary conditions, electronic states, adiabatic-to-diabatic transformation, two-state system, 304-309 Newton-Raphson equation, conical intersection location locations, 565 orthogonal coordinates, 567 Non-Abelian theory, molecular systems, Yang-Mills fields nuclear Lagrangean, 250 pure vs. tensorial gauge fields, 250-253 Non-adiabatic coupling ... 

Several methods for the determination of -y(R) have been proposed [224,225]. One is the direct computation of the non-adiabatic coupling matrix element ( i l(B 2))(r) by finite difference techniques, which gives the derivative of y (cf. Eq. (10)). Another is by supposing that the diabatic states adiabatic states Xk and Xkt are (almost) pure linear combinations of the two monomer states. This approximation can be made at the orbital level or at the A-electron level (or at both levels simultaneously). Also mixing matrix elements of molecular properties over adiabatic states may be used. 

---