Non-collinear magnetism and symmetries
Posted: Thu Dec 14, 2017 4:19 pm
Hello,
I tried to compute about the simplest conceivable non-collinear antiferromagnetic system, i.e. fcc Mn. The parameter file is added below. However, it dies with the complaint "out of memory in cg", which I can understand, given that it tried to allocate 7 GB of memory. The problem lies in the fact that it determined the space group to be P1, that is, no symmetry whatsoever, and thus wants to compute 1728 k-points. I would say that the space group should be at least P-4 3 m (#215), needing only 84 k-points, and actually it should even be a primitive unit cell when the orientation of the spinor is transformed along with the positions.
So is there some switch I have overlooked so that abinit recognizes the correct symmetry and thus is able to treat this problem, or is this a bug in the symmetry finder, or is this a kludge because the handling of symmetric non-collinearities is not implemented?
I tried to compute about the simplest conceivable non-collinear antiferromagnetic system, i.e. fcc Mn. The parameter file is added below. However, it dies with the complaint "out of memory in cg", which I can understand, given that it tried to allocate 7 GB of memory. The problem lies in the fact that it determined the space group to be P1, that is, no symmetry whatsoever, and thus wants to compute 1728 k-points. I would say that the space group should be at least P-4 3 m (#215), needing only 84 k-points, and actually it should even be a primitive unit cell when the orientation of the spinor is transformed along with the positions.
So is there some switch I have overlooked so that abinit recognizes the correct symmetry and thus is able to treat this problem, or is this a bug in the symmetry finder, or is this a kludge because the handling of symmetric non-collinearities is not implemented?
Code: Select all
#Definition of occupation numbers
occopt 4
tsmear 0.005
#Definition of the unit cell
acell 3*6.765
rprim 1 0 0 # FCC primitive vectors (to be scaled by acell)
0 1 0
0 0 1
#Definition of the atom types
ntypat 1
znucl 25
#Definition of the planewave basis set
ecut 25 # Maximal kinetic energy cut-off, in Hartree
pawecutdg 50.
#Exchange-correlation functional
ixc 11 # GGA PBE
#Definition of the k-point grid
shiftk 0. 0. 0.
kptrlatt
12 0 0
0 12 0
0 0 12
#Definition of the SCF procedure
iscf 17
nstep 50 # Maximal number of SCF cycles
tolvrs 1e-12
natom 4
typat 1 1 1 1
xred
-0.25 -0.25 -0.25
0.25 0.25 -0.25
0.25 -0.25 0.25
-0.25 0.25 0.25
spinat 0.5 0.5 0.5
-0.5 -0.5 0.5
-0.5 0.5 -0.5
0.5 -0.5 -0.5
nsppol 1
nspden 4
nspinor 2