C 3v versus C2v Cd(1S,3P,1P)–CH4 van der Waals complexes: A variational and perturbational multireference configuration interaction study

Abstract

Applications of a variational coupled-electron pair approach to the calculation of intermolecular interaction in the framework of the VB theory: Study of the van der Waals complex He-CH 4Ar and CH4 van der Waals complexes of 1 and 2fluoronaphthalene: A perturbed spherical top attached to a surface Accurate spectroscopic constants for the Cd(1 S,3 P,1 P)-H2 van der Waals complexes: A theoretical study J. Chem. Phys. 100, 8251 (1994); 10.1063/1.466768Halfcollision studies: Action spectroscopy of electronic energy transfer within the CdCH4 van der Waals complex The CdctS,3,lp)-CH 4 interaction is studied for the C 3v vertex-on Cd(IS,3,lp)-HCH 3 and face-on Cd(IS,3,lp)-H 3 CH approaches as well as the C 2v cdcIS,3,lp)-H 2 CH 2 edge-on approach of the metal atom to methane using extensive ab initio multireference configuration interaction plus second order multireference M011er-Plesset calculations. The ground state CdcIS)-CH 4 is totally repulsive for the C 3v vertex-on and C 2v edge-on approaches. Only a stable face-on CdeS)-H 3 CH complex was found. Although vertex-on and edge-on minima were found for the Cdep)-CH 4 excited complexes, they are less attractive than the corresponding Cde P)-H3CH face-on exciplexes. The optimal orientation of the face-on occupied 5p orbital of Cd(5s5p) is that which minimizes the overlap with C-H bonds leading to a ,,3rry" exciplex. For the CdctP)-CH 4 interaction, two face-on and two edge-on very stable complexes (all with De> 1300 cm-I ) were found. The CdctS)-H 3 CH cIA I ) complex was found to have a 185 cm-l well at 8.03 a.u. Both excited P states present shorter equilibrium distances-the Cdep)-H 3 CH eEl exciplex has a 799 cm-l well at 6.08 a.u., while the CdctP)-H 3 CH exciplex eE) has a 1337 cm-l well at 5.57 a.u. These results are in good agreement with the recent experimental values X IO+ctS)-CDe= 121 cm-l , R e =7.9 a.u.); A 30+ep)-(De=677 cm-I, R e =5.80 a.u.); and Ip-(De~1300 cm-I, R e =5.59 a.u.) obtained by Wallace and Breckenridge [J. Chem. Phys. 97, 2318 (1992)]. The present work confirms the C 3v facial nature of the observed ctS) ground and ep) excited complexes. The present results are inconclusive as to the facial or edge-on nature of the ~dctP)-CH4 exciplex, but they preclude the C 3v vertex-on possibility.

Accurate spectroscopic constants for the Cd(1S,3P,1P)–H2 van der Waals complexes: A theoretical study

“…The CIPSr (MRCI-MP2) ISt-3 p and ISt-l P transition energies with the totally uncontracted (111) 5p shell are only slightly improved with respect to those obtained with the partially contracted (21) 5p shell. 5 Once again, since we are comparing the computed S I t-3 p transition energy (29002 cm-I ) with the J-averaged value (31246 cm-I ) of the three finestructure states, the difference between these two values arises naturally from the non-negligible 2000 cm -1 splitting between the highest and the lowest spin-orbit components.…”

“…5 where we used only two 5 p orbitals leading to a (3s3p4d)/[111/211211] contraction. The CIPSr (MRCI-MP2) ISt-3 p and ISt-l P transition energies with the totally uncontracted (111) 5p shell are only slightly improved with respect to those obtained with the partially contracted (21) 5p shell.…”

Dynamics of the deactivation and desorption of Ba atoms from Ar clusters

“…These have motivated some complementary theoretical ab-initio studies. 17,18 Much of the early work has concentrated on singlet-to-triplet deactivation and has provided evidence for the breakdown of Wigner spin conservation rules 19 as the electron spin-orbit coupling strength increases with atomic mass. More recently the laser pump-probe experiments of Breckenridge and co-workers 20-22 on collisional deactivation of Cd( 1 P 1 ) has led to the proposal of a general mechanism for singlet-totriplet transfer which has successfully accounted for quenching in a range of isovalent metals including barium.…”

Reactions of Zn(4s4p 3P1) and Cd(5s5p 3P1) with SiH4

“…A variety of mechanisms, 1-62 at various levels of detail, have been proposed over the years to explain both the dominant products observed ͓͑1a͒, ͑1b͒, or ͑1c͔͒ and the distributions of MH(v,N) energies when process ͑1a͒ occurs. Ab initio calculations 18,22,[63][64][65][66][67][68][69][70] of M(nsnp) ϩ uX ͉ ͉ uH potential surfaces have also been reported which have sometimes been helpful mechanistically.…”