| Autor: |
D. Grimbert, V. Sidis, B. Lassier-govers |
| Rok vydání: |
1988 |
| Předmět: |
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| Zdroj: |
Chemical Physics. 124:187-204 |
| ISSN: |
0301-0104 |
| DOI: |
10.1016/0301-0104(88)87149-0 |
| Popis: |
An effective model-potential approach is devised in order to determine potential energy surfaces and interactions relevant to the study of non-adiabatic proton+molecule collisions. The procedure is illustrated on the low-lying 3A″ states of the H++O2 collisional system. The method is based on the determination of matrix elements of the electronic Hamiltonian in a basis of projected-valence-bond wavefunctions describing the incident state H++O2 (X3Σg−) and excited as well as charge exchange states generated by single orbital replacements from that state. Four approximations reduce the computational task to the mere evaluation of matrix elements of an O2 Fock-like operator F plus those of the proton-electron attraction term. The operator F is split into two terms. One term acts on the subspace spanned by the occupied SCF MO and related bound IVO of isolated O2 and is expressed as an effective Hamiltonian. The other term acts on the corresponding complementary space and involves a two-center screened Coulomb potential. Adiabatic states are computed and compared with available ab initio information. Diabatic states are built up using two methods: (M1) configuration interaction calculations in orthogonal subspaces and (M2) rotation of adiabaticstates achieving maximum overlap of the resulting states with strictly diabatic albeit crude prototypes. The characteristics of the diabatic crossing and related interaction between the 3A″ states correlating with the H++O2 (X3Σg−) and H + O2+ (X2Πg) asymptotes are determined for a broad sample of molecular geometries. Differences between the results of methods M1 and M2 appear only when the repulsive 3A″ state approaches and pseudo-crosses higher-lying 3A″ states. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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