[CPMD-list] about the Lanczos method

[Bako Imre]

Dear All
I tried to optimize the cell parameter of Palladium using differenet
functional.
I used the following input
&CPMD
WAVEFUNCTION OPTIMIZATION
SPLINE POINTS
  5000
nothing or the following two line
LANCZOS DIAGONALISATION
ANDERSON MIXING
 0.2
&END
&DFT
FUNCTIONAL PBE
&END
 &SYSTEM
   SYMMETRY
    2
   CELL
    7.062  1.0    1.0   0.0 0.0 0.0
   CUTOFF
   36.
TESR
  4 4 4
SCALED
POINT GROUP
  AUTO
&END
&ATOMS
*46-PdPBE.pp KLEINMAN-BYLANDER
  LMAX=D  LOC=S
   1
           .00000      .00000      .00000
 &END
I got the following results.
First case.  ELECTRONIC GRADIENT:
    MAX. COMPONENT =    0.42507E-05         NORM =    0.25111E-06
 NUCLEAR GRADIENT:
    MAX. COMPONENT =    0.00000E+00         NORM =    0.00000E+00


 TOTAL INTEGRATED ELECTRONIC DENSITY
    IN G-SPACE =                                        10.000000
    IN R-SPACE =                                        10.000000

 (K+E+L+N+X)         TOTAL ENERGY =             -28.47799365 A.U.
 (K)               KINETIC ENERGY =              27.90230418 A.U.
 (E=A-S+R)   ELECTROSTATIC ENERGY =             -32.79364868 A.U.
 (S)         ESELF                =              33.24518871 A.U.
 (R)         ESR                  =               0.00165652 A.U.
 (L) LOCAL PSEUDOPOTENTIAL ENERGY =              14.97342034 A.U.
 (N)   N-L PSEUDOPOTENTIAL ENERGY =             -33.27787919 A.U.
 (X)  EXCHANGE-CORRELATION ENERGY =              -5.28219030 A.U.
       GRADIENT CORRECTION ENERGY =              -0.10149011 A.U.



Second case (Using lanczos method)
 ELECTRONIC GRADIENT:
    MAX. COMPONENT =    0.88452E-03         NORM =    0.86514E-03
 NUCLEAR GRADIENT:
    MAX. COMPONENT =    0.00000E+00         NORM =    0.00000E+00


 TOTAL INTEGRATED ELECTRONIC DENSITY
    IN G-SPACE =                                        10.000000
    IN R-SPACE =                                        10.000000

 (B+E+X-V)           TOTAL ENERGY =             -29.05367185 A.U.
 (B)                  BAND ENERGY =              -4.56088319 A.U.
 (E=I-H-S+R) ELECTROSTATIC ENERGY =             -25.98640781 A.U.
 (S)         ESELF                =              33.24518871 A.U.
 (R)         ESR                  =               0.00380195 A.U.
 (X)  EXCHANGE-CORRELATION ENERGY =              -4.95568472 A.U.
 (V)  EXCHANGE-CORRELATION POTEN. =              -6.44930386 A.U.
       GRADIENT CORRECTION ENERGY =              -0.06196058 A.U.

This two results somehow very strange. Can you explain me why I see so
large difference between the two results.
Imre
Bakó Imre
MTA Kémiai Kutatóközpont, Kémiai Intézet
1525 Budapest Pf. 17
Telefon