ABINIT Discussion Forums

Dear colleges,
im new user, i use abinit for calculation materials my question is :
is is true to use all convergence of ecut, acell and nkpt in the same file like this for example ( i mean this actions in same file "acell:? 3*11.489
acell+? 3*2 and ecut: 10.0 ecut +3 and ngkpt: 4 4 4
ngkpt+ 1 1 1 ):
this is my input file
CdSe.in

ndtset 6 udtset 3 2
#Definition of the unit cell
acell:? 3*11.489
acell+? 3*2
optcell1? 1
ionmov1? 2
ntime1? 10
dilatmx1? 2.0
ecutsm1? 0.5

rprim 0.0 0.5 0.5
0.5 0.0 0.5
0.5 0.5 0.0

#Definition of the atom types
ntypat 2
znucl 48 34

#Definition of the atoms
natom 2 # There are two atoms
typat 1 2 # They both are of type 1, that is, Silicon.
xred
0.0 0.0 0.0
1/4 1/4 1/4

#Definition of the planewave basis set
ecut: 10.0 # Maximal kinetic energy cut-off, in Hartree
ecut +3
ecutsm 0.5
pawecutdg 100
#pawovlp 1

#Definition of the k-point grid
kptopt 1

ngkpt: 4 4 4
ngkpt+ 1 1 1
nshiftk 4
shiftk 0.5 0.5 0.5
0.5 0.0 0.0
0.0 0.5 0.0
0.0 0.0 0.5


#Definition of the SCF procedure
nstep 10 # Maximal number of SCF cycles
toldfe 1.0d-6 # Will stop when, twice in a row, the difference
# between two consecutive evaluations of total energy
# differ by less than toldfe (in Hartree)
# This value is way too large for most realistic studies of materials
diemac 12.0 # Although this is not mandatory, it is worth to
# precondition the SCF cycle. The model dielectric
# function used as the standard preconditioner
# is described in the "dielng" input variable section.
# Here, we follow the prescription for bulk silicon.
# add to conserve old < 6.7.2 behavior for calculating forces at each SCF step
optforces 1


thanks a lot
M.Hocine TEDJINI

No !

You have to set 2 parameters and converge the 3rd one at the same time.

The best you can do is use the double loop dataset (udtset) to run a convergence study on 2 parameters
udtset 5 9
jdtset 45 # 5*9
ngkpt:? 2 2 2
ngkpt+? 2 2 2
ecut?: 10
ecut?+ 2

Ah okay, i think by your example you can converge etotal with ( ecut and nkpt) and acell with (ecut and nkpt) ?
thanks a lot Mr.Jordan

To converge acell with my example, you would indeed need to optimize the cell for each dataset so no need for ? or : or +
optcell 1
ionmov 2
ntime 10
dilatmx 2.0
ecutsm 0.5