CCL: TDDFT/RPA B matrix

[John McKelvey <jmmckel(~)gmail.com>]

 Folks,

In RPA and TDDFT the A matrix is the same as a CIS matrix, and the
 B matrix is referred to a de-excitation matrix.  The latter makes sense
 when you look compare some of the terms in each matrix.  The A matrix is
 also referred to as a linear response.  I have heard the B matrix referred
 to as being related to a magnetic related issue (ring currents, maybe.) 
 
I would be happy to get people's more comprehensive physical pictures of
 the B matrix, and if "defined" physical pictures for the A+B, and A-B
 matrices.

Regards,

John McKelvey