CCL:G: incremental and nonincremental Fock matrix

[Simen Reine <simen.reine-*-kjemi.uio.no>]

 Sent to CCL by: Simen Reine [simen.reine_-_kjemi.uio.no]
 Hi Reza,
The Fock matrix F(D) consist of a one-electron, h, and a two-electron
 contributuion (that depends on the density-matrix D), G(D), accoring to
 F(D) = h + G(D).
In the non-incremental Fock matrix scheme the full Fock matrix is
 built in
 each SCF iteration, whereas in the incremental Fock matrix scheme the
 Fock
 matrix is built by adding only the two-electron correction (or
 increment)
 to the Fock matrix of the previous SCF iteration
 F(D) = F(D') + G(D'-D)
where D is the current and D' the previous density matrix. The
 incremental
 Fock matrix construction is typically much more efficient since the
 difference between the two densities is small - thus allowing for more
 efficient screening.
 Hope this helps!
 On Thu, 8 Mar 2012, 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.
>  ">
 ______________________________________________________________
 Dr. Simen S. Reine, Researcher at the
 Centre for Theoretical and Computation Chemistry (CTCC)
 Department of Chemistry     E-mail: simen.reine{=}kjemi.uio.no
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