ABINIT Discussion Forums

Dear friends,

i am currently trying to run gamma phonon calculation in 4h GaAs, so according the nlo tutorial i made following input

# Linear and nonlinear response calculation for AlAs
# Perturbations: electric fields & atomic displacements
# (M. Veithen, 21.4.2005)

#Definition of lattice parameters
#********************************
acell 7.3926115459E+00 7.3926115459E+00 2.4343461639E+01
rprim 5.0000000010E-01 -8.6602540370E-01 0.0000000000E+00
5.0000000010E-01 8.6602540370E-01 0.0000000000E+00
0.0000000000E+00 0.0000000000E+00 1.0000000000E+00

#Definition of atomic positions and types
#*************************************
natom 8
ntypat 2
znucl 31 33
typat 4*1 4*2
xred -6.3633415397E-09 1.5233758324E-07 1.8680818754E-01
-2.1818360876E-07 -1.9010575268E-08 6.8680815738E-01
3.3333331861E-01 6.6666684149E-01 4.3721796994E-01
6.6666650478E-01 3.3333332746E-01 9.3721789265E-01
-1.5967159161E-07 -5.1799357254E-10 3.6262574184E-04
-2.7297424114E-08 1.7058147241E-07 5.0036265620E-01
3.3333332814E-01 6.6666681624E-01 2.4961129047E-01
6.6666645999E-01 3.3333331142E-01 7.4961122008E-01
ixc 3

#Parameters of the SCF cycles
#****************************
iscf 5
nstep 1200

#Plane wave basis and k-point grid
#*********************************
ecut 15
ecutsm 0.5
dilatmx 1.05
ngkpt 8 8 8
nshiftk 1
shiftk 0 0 0.5

ndtset 5 jdtset 1 2 3 4 5

#DATASET1 : scf calculation: GS WF in the BZ
#********************************************
prtden1 1
kptopt1 1
toldfe1 1.0d-12

#DATASET2 : non scf calculation: GS WF in the whole BZ
#*****************************************************
getden2 1
kptopt2 2
iscf2 -2
getwfk2 1
tolwfr2 1.0d-22
nband2 17


#DATASET3 : ddk on the MP grid of k-points
#*****************************************
getwfk3 2
rfdir3 1 1 1
rfelfd3 2
tolwfr3 1.0d-22
nband3 17
kptopt3 2

#DATASET4 : ddE on the MP grid of k-points
#*****************************************
prtden4 1
getwfk4 2
getddk4 3
rfdir4 1 1 1
rfphon4 1
rfatpol4 1 2
tolvrs4 1.0d-12
rfelfd4 3
nband4 17
kptopt4 2
prepanl4 1

#DATASET5 : 3DTE calculation
#***************************
getden5 1
get1den5 4
getwfk5 2
get1wf5 4
nband5 17
kptopt5 2
optdriver5 5
rf1elfd5 1
rf1phon5 1
rf1atpol5 1 2
rf1dir5 1 1 1
rf2elfd5 1
rf2dir5 1 1 1
rf3elfd5 1
rf3dir5 1 1 1

nbdbuf 0

when code approaches to ds5 suddenly appears an error: initmv: ERROR -
In a non-linear response calculation, nband must be equal
to the number of valence bands.

and then it stops(
what does it mean? why it is imposible to take explicit value 17?
any ideas?

It kinda strange, because when i set nband 16 it runs correctly, but nband 17 or 15 are not correct...
And yes, for 4h structure with 8 atoms in prim cell it should be rfatpol4 1 8 instead of rfatpol4 1 2 and so on, my bad.
Please, someone, explain me that confusing situation about nband value.

Best wishes,
Alexander Koskin;

In this kind of calculation you must have nband set to the number of filled valence bands, no more and no less--in your case this number is evidently 16 (4 Ga and 4 As in the unit cell, so 32 electrons total).

i get it, thanx;
all the best,
Magniff