Intramolecular dependence of the frequency-dependent polarizabilities K2(a3∑ut) and van der Waals dispersion coefficients for X + K2, X2 + K and X 2 + K2 (X = Li,Na,K)
Résumé
The ab initio time-dependent gauge-invariant method has been used to compute the frequency-dependent dipole polarizabilities of the first triplet state of K2(a3∑u+), and to study its dependence on the internuclear distance. Then, isotropic C 6000 and anisotropic C6202 long-range coefficients of X(2S) + K2(a 3∑u+), K(2S) + X 2(a3∑u+) and X 2(a3∑u+) + K2(a 3∑u+) (X = Li,Na,K) have been evaluated using dynamic dipole polarizability values of K and K2. From the determination of the dynamic quadrupole polarizability components of both interacting species, C8000, C8202 and C8404 have been also obtained for the X(2S) + K2(a3∑u+) and K( 2S) + X2(a3∑u+) (X = Li,Na,K) interacting systems at the calculated equilibrium distance of K 2 (11.57 bohr), as well as the three-body C9 long-range coefficients depending only on the dipole polarizability of K. Good agreement with the previous values of Marinescu and Starace [Phys. Rev. A 55 (1997) 2067] is obtained for these last coefficients. © 2003 Elsevier B.V. All rights reserved.