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285. KOMMUT: A Program to Evaluate Commutators and
Averages of Operators Composed of Simple Fermion
Creation and Annihilation Operators
by George Purvis and Christoph Nehrkorn, Quantum Theory Project, University of Florida, Gainesville, Florida 32611 This program evaluates commutators between composite Boson-like operators (e.g., aI +aJ or aI +aJ +aK aL) and anti-commutators between composite Fermion-like operators (e.g., aI, aJ+, aI +aJ aK). The composite operators are composed of simple creation (aI+) and annihilation (aJ spin-orbital field operators, obeying the commutation relations).
The program evaluates anti-commutators between two Fermion-like operators (odd number of simple opeators) and commutators otherwise. From this result, the average with respect to any determinant which can be obtained from the Hartree-Fock ground state (HFGS) is taken. The excited determinants are incorporated by adding the simple operators, which produce this determinant from the HFGS to the left and/or right side of the result of the previous commutations. FORTRAN IV (IBM) Lines of Code: 1593 Recommended Citation: G. Purvis and C. Nehrkorn, QCPE 11, 285 (1975). |