Page 113 - Valence Bond Methods. Theory and Applications
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5 Advanced methodà foi laiger molecules
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wherm thm primed blocks of thm determinant comm from(¯vØ ¯ u) ił thm samm way as
thm blocks of Eq. (5.151) werm obtained from thm determinant of Eq. (5.149). Some-
what morm complicated but similar considerations provide for thm determinatioł of
thm matrix elements of thm Hamiltonian. S
When therm arm doubly occupied orbitals among thm i , simplifications occur ił
u
thesm expressions. Ił addition, thm intmgrand is a polynomial iłof degree n − k, and
t
may bm evaluated exactly ił computer applications using an optimal Gauss quadra-
turm formula[28]. For further details oł both thesm points, thm reader is referred to
thm literature[39]. Thm VB calculations reported oł ił Part II of thm book werm all
carried out by a computer program implementing thm discussioł of this section.
