Hi everyone,
I am traying to perform a scf calculation for a 756 atoms supercell nanoribbon
(for a phonon -phonopy- calculation). The problem is that it using the next
input:
&control
calculation = 'scf'
prefix='grapheneph',
pseudo_dir = './',
outdir='./saleph62/'
/
&system
ibrav = 0,
nat = 756,
ntyp = 1,
occupations = 'smearing',
smearing = 'gaussian',
degauss = 0.01,
ecutwfc = 60.D0,
ecutrho = 500.D0,
/
&electrons
conv_thr = 1.D-8,
diagonalization = 'cg',
mixing_mode = 'plain',
/
K_POINTS gamma
! ibrav = 0, nat = 756, ntyp = 1
CELL_PARAMETERS bohr
89.4600000000000080 0.0000000000000000 0.0000000000000000
0.0000000000000000 48.4470000000000027 0.0000000000000000
0.0000000000000000 0.0000000000000000 10.0000000000000000
ATOMIC_SPECIES
C 12.01070 C.pbe-rrkjus.UPF
ATOMIC_POSITIONS crystal
[756 Carbon atoms...]
Requires Estimated max dynamical RAM per process > 64279.60Mb of memory, which
results in a memory allocation error, since I ''only'' have 65Gb of memory in
my computer.
I have already read across this forum and pages from the QE manual, where it
suggests using a gamma k-point for instance. But i do not know if this huge
amout of memory required is normal, or is due to some absurd input option I am
using.
Using electron_maxstep = 50 tag does not lead to a memory error, although it is
quite slow.
Solving with this same input for a 1x1x1 supercell (78 atoms), it works
perfectly.
Any ideas why I am having this problem? Should I use other input options for
this system?
Thank you for your time and patience.
Pablo.
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