[CPMD-list] about the optimalisation of bulk PD

[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
LANCZOS DIAGONALISATION
ANDERSON MIXING
 0.2
&END
&DFT
FUNCTIONAL PZ
&END
 &SYSTEM
   SYMMETRY
    2
   CELL
    7.062  1.0    1.0   0.0 0.0 0.0
   CUTOFF
   36.
TESR
  4 4 4
SCALED
KPOINTS MONKHORST-PACK
 5 5 5
POINT GROUP
  AUTO
&END
&ATOMS
*46-Pdldapz.pp KLEINMAN-BYLANDER
  LMAX=D  LOC=S
   1
           .00000      .00000      .00000
 &END
I changed the cell size and see the total energy.
I got the following results.
6.902	-28.7066
7.002	-28.71231
7.032	-28.70967
7.062	-28.70686
7.092	-28.70397
7.122	-28.6998
7.152	-28.69584
7.182	-28.73076
7.202	-28.73065
7.232	-28.72769
7.242	-28.72694
7.262	-28.74845
7.282	-28.74751
7.302	-28.74469
7.362	-28.73728
7.462	-28.72374
	
If you see these data you can find three different minima on this curve.
This is a bit suprising me.
Can you explain this behaviour?
Imre
Bakó Imre
MTA Kémiai Kutatóközpont, Kémiai Intézet
1525 Budapest Pf. 17
Telefon