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Hello

I am a new VASP user. I am using vasp.5.2.12. I try to optimise a bulk structure having Al, Ca,O and I have chosen the following options.

Pseudo potentials: PAW
XC: GGA-PE
PREC = High

I did optimisation [ both ionic positions and cell] in this structuree

Optimisation gave me a deviation of 0.9 Ang from the expt or initial. Can any one comment on this?

INCAR

SYSTEM = C12A7_2O geometry optimisation

Start parameter for this run
ISTART = 0
ICHARGE = 2
INIWAV = 1

Electronic and Ionic Relaxation
PREC = High
NSW = 100
IBRION = 2
POTIM = 0.5
EDIFFG = -0.04
NELM = 40
NELMIN = 2
EDIF = 10E-4
ISIF = 3
ISPIN = 1
GGA = PE

DOS related values
ISMEAR = 0 ; SIGMA = 0.1

POSCAR

C127A_2O
1.000 ! universal scaling parameters
11.98748 0.000000 0.000000 ! lattice vector a
0.000000 11.98748 0.000000 ! lattice vector b
0.000000 0.000000 11.98748 ! lattice vector c
24 28 66 ! number of atoms: 24 Ca atoms: 28 Al atoms: 66 O atoms in the same order
cart ! positions in cartesian coordinates
X X X

KPOINTS

K-Points ! Comment
0 ! 0=automatic generation of k-points
Monkhorst Pack ! M use Monkhorst Pack
2 2 2 ! grid 2x2x2
0 0 0 ! shift (usually 0 0 0)



Can anyone comment on this please?


regards
Kugan75

Do you have a proble with the result you obtain? If so, then what is the question you wish to ask?

Danny