[CPMD-list] ODIIS with k points

[Eung-Gun Kim]

Dear List Subscribers,

I am running density optimization on a hydrocarbon crystal using v3.9.1 on IBM
SP4 (p655).  Following Axel's warning on a combined use of ODIIS and k points, I
ran a couple of runs to make sure results are reasonable in comparison with
those from a Lanczos calculation.  What puzzles me is that when I "PRINT ON
FORCES EIGENVALUES," energies change from those without these key
words---although not significant.  LANCZOS DIAGO seems very robust and stable,
but the calculation takes 10 times longer than ODIIS, at least in this
particular case.

Another question is that ELECTROSTATIC ENERGY from LANCZOS is very different
than that from ODIIS.  The fact that TOTAL ENERGY is very similar in both cases
only suggests that this term may refer to a different quantity, depending on
which optimization method you use.

Regards,

EG Kim


ODIIS with PRINT ON FORCES EIGENVALUES -----------------------------------------

 (K+E1+L+N+X)           TOTAL ENERGY =         -122.64331840 A.U.
 (K)                  KINETIC ENERGY =           14.43425982 A.U.
 (E1=A-S+R)     ELECTROSTATIC ENERGY =         -125.12750514 A.U.
 (S)                           ESELF =          134.04460621 A.U.
 (R)                             ESR =            3.42570289 A.U.
 (L)    LOCAL PSEUDOPOTENTIAL ENERGY =          -65.96540035 A.U.
 (N)      N-L PSEUDOPOTENTIAL ENERGY =           12.56202777 A.U.
 (X)     EXCHANGE-CORRELATION ENERGY =          -40.79762548 A.U.
          GRADIENT CORRECTION ENERGY =           -1.86569866 A.U.


ODIIS without PRINT ON FORCES EIGENVALUES --------------------------------------

 (K+E1+L+N+X)           TOTAL ENERGY =         -122.64331838 A.U.
 (K)                  KINETIC ENERGY =           14.43425982 A.U.
 (E1=A-S+R)     ELECTROSTATIC ENERGY =         -125.12751216 A.U.
 (S)                           ESELF =          134.04460621 A.U.
 (R)                             ESR =            3.42570289 A.U.
 (L)    LOCAL PSEUDOPOTENTIAL ENERGY =          -65.96541815 A.U.
 (N)      N-L PSEUDOPOTENTIAL ENERGY =           12.56201664 A.U.
 (X)     EXCHANGE-CORRELATION ENERGY =          -40.79762829 A.U.
          GRADIENT CORRECTION ENERGY =           -1.86569863 A.U.

LANCZOS DIAGO ------------------------------------------------------------------

 (B+E2+X-V)             TOTAL ENERGY =         -122.64331846 A.U.
 (B)                     BAND ENERGY =          -21.22863427 A.U.
 (E2=I-H-S+R)   ELECTROSTATIC ENERGY =         -113.55043258 A.U.
 (S)                           ESELF =          134.04460621 A.U.
 (R)                             ESR =            3.42570289 A.U.
 (X)     EXCHANGE-CORRELATION ENERGY =          -40.79763615 A.U.
 (V)     EXCHANGE-CORRELATION POTEN. =          -52.93338459 A.U.
          GRADIENT CORRECTION ENERGY =           -1.86569859 A.U.

--------------------------------------------------------------------------------