An AB initio study of molecular structures, force fields, and vibrational spectra of transition metal trifluorides MF{sub 3} (M = Sc, Ti,V,Cr,Mn,Fe,Co,Ni)
- Ivanova State Acedemy of Chemistry and Technology (Russian Federation)
An ab initio theoretical study was carried out on MF{sub 3} molecules to determine theirs ground electronic state geometries, force fields, and vibrational spectra, using basis sets (14sl1p6d1f/9s5pid){r_arrow}(10s8p3dlf/4s2pld). All of the molecules except MnF{sub 3} have been studied by spin and symmetry restricted Martree-Fock method (RHF). Configuration interaction calculations were carried out on ScF{sub 3}, CrF{sub 3}, and MnF{sub 3}. Single reference CISD+Q level of theory was used for ScF{sub 3}. Complete active space (CASSCF) calculations were performed on CrF{sub 3} and MnF{sub 3} in order to select the reference configurations for the final second order CI calculation (SOCI), which allows all single and double excitations out of a complete active space. At RHF level we find all of the molecules to be trigonal splanar D{sub 3h}, with the exception of CrF{sub 3} and NiF{sub 3}, molecule with extremely low barrier to planarity is in fact quasiplanar. The conclusion regarding the geometry of CrF{sub 3} is obviously unreliable, since our calculations have shown the D{sub 3h} molecule CrF{sub 3} is obviously unreliable, since our calculations have shown the D{sub 3h} molecule CrF{sub 3} to be Hartree-Fock unstable. At SOCI level of theory we find CrF{sub 3} to be planar D{sub 3h}. The lowest D{sub 3h} electronic state of MnF{sub 3} is {sup 5}E{prime}. The Jahn-Tellar surface has been studied. The three minima on this surface correspond to the {sup 5}A{sub l} minimum, and 2515 cm{sup {minus}1} below the D{sub 3h} energy, and are separated by 726 cm{sup {minus}1} barriers corresponding to the {sup 5}B{sub 2} {open_quotes}minimum{close_quotes}. These values show that the Jahn-Teller effect is mainly static and the molecular structure and the low-lying vibronic energy levels of MnF{sub 3} may be roughly treated within adiabatic approximation.
- OSTI ID:
- 447553
- Report Number(s):
- CONF-960343-; TRN: 97:005450
- Resource Relation:
- Conference: 2. international congress on theoretical chemical physics, New Orleans, LA (United States), 9-13 Mar 1996; Other Information: PBD: 1996; Related Information: Is Part Of Second international congress on theoretical chemical physics - ICTCP II; PB: 90 p.
- Country of Publication:
- United States
- Language:
- English
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