problem with converging energy

[bmalvandi]

hello
I want to calculate phonon frequencies for LaCoO3 and in first step I ran first program of 5th lesson but even with 200 nstep
energy didn't converge!
I think maybe I want to change dimac but I don't know what must I do!
please help me
thanks
my inputs are:

# Crystalline LaCoO3
#

#Specific to ground state calculation
kptopt 1

tolvrs 1.0d-18
iscf 7


#######################################################################
#Common input variables

#Definition of the unit cell
acell 3*7.22
rprim 1.0 0.0 0.0
0.0 1.0 0.0
0.0 0.0 1.0
#Definition of the atom types
ntypat 3
znucl 57 27 8

#Definition of the atoms
natom 5
typat 1 2 3 3 3
xred
0.0 0.0 0.0
1/2 1/2 1/2
0.5 0.5 0.0
0.5 0.0 0.5
0.0 0.5 0.5
#Gives the number of band, explicitely (do not take the default)
nband 15

#Exchange-correlation functional
ixc 1

#Definition of the planewave basis set
ecut 45.0

#Definition of the k-point grid
kptrlatt -4 4 4
4 -4 4
4 4 -4

#Definition of the SCF procedure
nstep 100
diemac 5000.0

[gonze]

Hi,

Are you sure your system is insulating with LDA ?
You might try with occopt 7, and more bands .
If it is indeed insulating, then diemac should be much smaller, likely.
Do you have an idea of the dielectric constant of your material ?

X.