scholarly journals Analytic second derivatives in restricted Hartree–Fock theory. A method for high‐spin open‐shell molecular wave functions

1982 ◽  
Vol 77 (11) ◽  
pp. 5647-5654 ◽  
Author(s):  
Paul Saxe ◽  
Yukio Yamaguchi ◽  
Henry F. Schaefer
Keyword(s):  
High Spin ◽  
Open Shell ◽  
Wave Functions ◽  
Hartree Fock ◽  
Second Derivatives

MO-Theoretical Studies on a Model Complex for Deoxymyoglobin

1998 ◽  
Vol 53 (9) ◽  
pp. 755-765
Author(s):  
Christian Kollma ◽  
Sighart F. Fischer ◽  
Michael C. Böhm
Keyword(s):  
High Spin ◽  
Ground State ◽  
High Spin State ◽  
Open Shell ◽  
Spin States ◽  
Hartree Fock ◽  
Intermediate Spin ◽  
Model Complex ◽  
Out Of Plane ◽  
Overlap Method

AbstractThe origin of the displacement of the Fe atom in deoxymyoglobin with respect to the porphyrin plane in the high-spin state is examined by a qualitative molecular orbital (MO) analysis on the extended Hückel level. We find that attachment of a fifth ligand (imidazole in our model complex) to Fe(II)porphyrin favors the out-of-plane shift due to a strengthening of the bonding interaction between Fe and the nitrogen of the imidazole ligand. This results in a high-spin (5 = 2) ground state with Fe shifted out-of-plane for the five-coordinate complex instead of an intermediate spin ground state (5 = 1) with Fe lying in the plane for four-coordinate Fe(II)porphyrin. The relative energies of the different spin states as a function of the distance between Fe and the porphyrin plane are evaluated using an ROHF (restricted open shell Hartree-Fock) version of an INDO (intermediate neglect of differential overlap) method. We observe a level crossing between high-spin and intermediate spin states whereas the low-spin (5 = 0) state remains always higher in energy.

On methods for converging open-shell Hartree-Fock wave-functions

1974 ◽  
Vol 28 (3) ◽  
pp. 819-828 ◽  
Author(s):  
M.F. Guest ◽  
V. R. Saunders
Keyword(s):  
Open Shell ◽  
Wave Functions ◽  
Hartree Fock
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