Fock matrix skeleton

The foundations of the use of symmetry in SCF calculations were laid by Dacre, Elder,and Dupuis and King." The original methodology was later extended to many other aspects of electronic structure calculations, including energy second derivatives." In the SCF procedures, symmetry blocking is employed at two levels. First, the skeleton Fock matrix in each iteration is con-... 

The matrices H and J are the one- and two-electron parts, respectively, of the skeleton (core) first derivative Fock matrix in the CO basis. The definitions of these matrices are obtained from their molecular counterparts51 by substituting instead of the MO coefficents cm[Pg.469]

Now, from our manipulations above we can easily see that F can be constructed from a skeleton matrix obtained using only a P2 list, since the Fock operator is totally symmetric. However, this far from ideal, since we would like to avoid the redundancies that arise unless we use the Pi list of two-electron integrals, or, here, supermatrix elements. We define first a matrix Y(IJKL) with the property that the IJ block is given by... 

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