I'm trying to calculate the optical properties of Barium Titanate in it's P4mm phase. Following the optics tutorial, I calculated the linear response with 4 * 4 * 4 and 8 * 8 * 8 K-grid. Obviously, they were not very accurate. For accuracy, I decided to use 24 * 24 * 24 kpoint-grid. To make sure my computer (Intel core i5, 4 GB RAM, Win 7 32 bit) can handel the memory need, I used mffmem 0 mkmem 500 mkqmem 500 mk1mem 500. After 21 hours, I got the WFK files necessary to run the next optics run.
But the problem is that the wfk files are 6~7 GB in size and optic is crashing with this error:
"Operating system error: Can not allocate memory Out of memory."
At this point I'm lost. Is it at all possible to handle a wfk file that big on a single PC (keeping my computer's specification in mind)?
Here is the input file to abinit:
Code: Select all
#Prepare the computation of linear and non-linear optic properties
#of GaAs crystal : ground-state with few bands,
#then non-SCF with a larger number of bands, then ddk for different directions
#Note that the k point sampling shoud be finer for significant results. The cut-off energy is also too low.
ndtset 6
#First dataset : SC run with kpoints in the IBZ
iscf1 3
nband1 40
nstep1 1000
kptopt1 1
nbdbuf1 0
prtden1 1 getden1 0 getwfk1 0 ! Usual file handling data
#Second dataset : NSC run with large number of bands, and points in the IBZ
iscf2 -2
nband2 40 ! This number of bands might be too low for non-linear optics and real part of linear optics
nstep2 1000
kptopt2 1
getwfk2 1 getden2 1 ! Usual file handling data
#Third dataset : NSC run with large number of bands, and points in the the full BZ
iscf3 -2
nband3 40 ! This number of bands might be too low for non-linear optics and real part of linear optics
nstep3 1000
kptopt3 3
getwfk3 2 getden3 1 ! Usual file handling data
#Fourth dataset : ddk response function along axis 1
iscf4 -3
nband4 40 ! This number of bands might be too low for non-linear optics and real part of linear optics
nstep4 1 nline4 0
kptopt4 3
nqpt4 1 qpt4 0.0d0 0.0d0 0.0d0
rfdir4 1 0 0
rfelfd4 2
getwfk4 3
#Fifth dataset : ddk response function along axis 2
iscf5 -3
nband5 40 ! This number of bands might be too low for non-linear optics and real part of linear optics
nstep5 1 nline5 0
kptopt5 3
nqpt5 1 qpt5 0.0d0 0.0d0 0.0d0
rfdir5 0 1 0
rfelfd5 2
getwfk5 3
#Sixth dataset : ddk response function along axis 3
iscf6 -3
nband6 40 ! This number of bands might be too low for non-linear optics and real part of linear optics
nstep6 1 nline6 0
kptopt6 3
nqpt6 1 qpt6 0.0d0 0.0d0 0.0d0
rfdir6 0 0 1
rfelfd6 2
getwfk6 3
#Data common to all datasets
nshiftk 1
shiftk 0.5 0.5 0.5
ngkpt 24 24 24 ! This is much too low : should be at least 24x24x24
mffmem 0
mkmem 500
mkqmem 500
mk1mem 500
acell 7.5124752684E+00 7.5124752684E+00 7.6906441898E+00
amu 1.37327000E+02 4.78800000E+01 1.59994000E+01
diemac 4.00000000E+03
ecut 10.00 ! This is also too low
iscf 3
ixc 11
natom 5
ntypat 3
rprim 1 0 0 0 1 0 0 0 1
xred 0.0000000000E+00 0.0000000000E+00 0.0000000000E+00
5.0000000000E-01 5.0000000000E-01 5.1430000000E-01
5.0000000000E-01 5.0000000000E-01 -3.0760000000E-02
5.0000000000E-01 0.0000000000E+00 4.8481703472E-01
0.0000000000E+00 5.0000000000E-01 4.8481703472E-01
nbdbuf 10
# tnons 72*0.0
typat 1 2 3 3 3 tolwfr 1.e-20
znucl 56 22 08
Here is the input file to optic
Code: Select all
toptic_1_o_DS4_1WF16
toptic_1_o_DS5_1WF17
toptic_1_o_DS6_1WF18
toptic_1_o_DS3_WFK
0.002 ! Value of the smearing factor, in Hartree
0.0003 0.3 ! Difference between frequency values (in Hartree), and maximum frequency ( 1 Ha is about 27.211 eV)
0.000 ! Scissor shift if needed, in Hartree
0.002 ! Tolerance on closeness of singularities (in Hartree)
3 ! Number of components of linear optic tensor to be computed
11 22 33 ! Linear coefficients to be computed (x=1, y=2, z=3)
2 ! Number of components of nonlinear optic tensor to be computed
123 222 ! Non-linear coefficients to be computed
Any help or comment would be greatly appreciated.