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[mamikon Gulian <mamikon.armen.gulian@gmail.com>]

Got it after some playing and convergence testing. ECUT = 14 ate up all the RAM. 

Sorry for the disturbance,

M.G.

On Wed, Sep 16, 2009 at 12:23 AM, <mamikon.armen.gulian@gmail.com> wrote:

Hello abiniters,

For exercise I have been trying to calculate the response function of Si with
abinit. For that purpose I modified the file toptic_1.in from the tutorial to
fit Si.It is shown below. My ecut = 14 and my k-point grid = 24x24x24. These
values are the minimum requirement for any degree of accuracy. This is the
portion before the use of the command "optic"; i.e., I make the command "abinis
< toptic_1.files> log".

The run takes a long time but the real problem is in the memory. The combined,
generated files take up over a dozen gigabytes and sometimes the 32-GB-RAM
computer that I am using runs out of RAM.

Is there any way around this? I think I am making some mistake. It's hard to
believe that these calculations could require such exclusive amounts of memory
(especially since 24^3 is the minimum).

Any input or advice on this would be very much appreciated, as even the
slightest modification could free some memory.

Thanks again,
-MG

INPUT:

#Prepare the computation of linear and non-linear optic properties
#Si 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  4
 nstep1 25
 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 20  ! This number of bands might be too low for non-linear optics and
real part of linear optics
  nstep2 25
 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 20  ! This number of bands might be too low for non-linear optics and
real part of linear optics
  nstep3 25
 kptopt3  3
 getwfk3  2   getden3 1   ! Usual file handling data


#Fourth dataset : ddk response function along axis 1
  iscf4 -3
 nband4 20   ! 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 20   ! 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 20   ! 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 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
 ngkpt  24 24 24 # 10 10 10 !This is much too low:should be at least 24x24x24

 acell   3*10.27
 amu 28.0855 28.0855
 diemac 12.0
 ecut 14           #7 ! This is also too low
 iscf 3
 ixc 3
 natom  2 nbdbuf 2
 ntypat 1
 rprim   0 .5 .5  .5 0 .5  .5 .5 0
 xred 3*0.00d0 3*0.25d0
 tnons 72*0.0
 typat  1 1  tolwfr  1.e-20
 znucl 14 14