CCL:G: incremental and nonincremental Fock matrix

[Heribert Reis <hreis- -eie.gr>]

 Sent to CCL by: Heribert Reis [hreis###eie.gr]
 Dear Reza,
 NoIncFock calculates the Fock-matrix from scratch at each SCF step,
 which is expensive, but accurate.
 IncFock approximates the Fock-matrix by adding up the changes due to the
 density matrix change from consecutive steps of the SCF:
 F(P_i) = F(P_i-1) + F(P_i - P_i-1), where P is the density.
 This is faster than NoIncFock, and the approximation is a good one, if
 the density changes are small, e.g. close to convergence, but may also
 fail.
 Heribert
 On Thu, 2012-03-08 at 05:45 -0500, Reza Shojaei shojaei81[A]gmail.com
 wrote:
 > Sent to CCL by: "Reza  Shojaei" [shojaei81%%gmail.com]
 > Dear all,
 >
 > Do you have any idea about the exact meanning of incremental Fock  matrix
 which is default setting for direct SCF.
 > What's the non incremental fock matrix?
 > here I put the Gaussian's manual which I don't understand:
 > "IncFock:
 > Forces use of incremental Fock matrix formation. This is the default for
 direct SCF. NoIncFock prevents the use of incremental Fock matrix formation, and
 it is the default for conventional SCF. ">
 >