Dear Pooja
I might not have understooo what you want to do.
Looking at your input it looks like you are not actually computing the energy
of an isolated system, but instead the energy of
rocksalt CaO. In that case it is not isolated system, remove assume_isolated
from the input, use sensible values for alat and the computation should
converge.
Pietro
Sent from Mail for Windows 10
From: Pooja Vyas
Sent: Saturday, June 27, 2020 11:56 AM
To: Quantum ESPRESSO users Forum
Subject: Re: [QE-users] Energy of isolated atom of CaO
I tried the way you suggested, tried replacing "relax" by "scf", however , I
still face the same issue: No convergence even after 100 iterations. Following
is the input file:
PS: I want to calculate isolated energy of CaO using example05/PW (i.e
Martyna-Tuckerman) method.
#!/bin/sh
for a in 30
do
cat > ${a}.in << EOF
&CONTROL
calculation = 'relax'
prefix = "${a}",
pseudo_dir = "/home/userpooja/pv/cohesive/pseudo/",
outdir = "/home/userpooja/pv/cohesive/",
/
&SYSTEM
ibrav = 1,
celldm(1) = $a,
nat = 2,
ntyp = 2,
ecutwfc = 100.D0,
nbnd = 8
assume_isolated = 'martyna-tuckerman'
/
&ELECTRONS
conv_thr = 1.D-8,
mixing_beta = 0.7D0,
startingwfc = 'random'
/
&IONS
/
ATOMIC_SPECIES
Ca 40.078 Ca.pbe-nsp-van.UPF
O 15.999 O.pbe-van_ak.UPF
ATOMIC_POSITIONS
Ca 0.0 0.0 0.0
O 0.5 0.5 0.5
K_POINTS Gamma
EOF
mpirun -np 40 -machinefile x1 /apps/codes/qe/6.4/bin/pw.x < ${a}.in > ${a}.out
done
Any kind of help is appreciated.
Thanks and Regards.
On Fri, Jun 26, 2020 at 11:58 AM Pietro Delugas <[email protected]> wrote:
Hello
In ATOMIC_POSITIONS you need to specify the units that you are using for the
coordinates, if you don’t put anything he program assumes alat units and puts
the 2 atoms very far apart.
If you actually wanted compute the two separated atoms specifying
startingwfc=’random’ in the &electrons name list may help. In this case I
would also chose calculation=’scf’ in &control.
Regards - Pietro
Sent from Mail for Windows 10
From: Pooja Vyas
Sent: Friday, June 26, 2020 8:12 AM
To: Quantum ESPRESSO users Forum
Subject: [QE-users] Energy of isolated atom of CaO
Dear users,
I want to calculate cohesive energy of CaO. I'm using cluster_example/PW which
uses assume_isolated = 'martyna_tuckerman' . Following is my input script:
#!/bin/sh
for a in 30
do
cat > ${a}.in << EOF
&CONTROL
calculation = 'relax'
prefix = "${a}",
pseudo_dir = "/home/user/pv/cohesive/pseudo/",
outdir = "/home/user/pv/cohesive/",
/
&SYSTEM
ibrav = 1,
celldm(1) = $a,
nat = 2,
ntyp = 2,
ecutwfc = 100.D0,
assume_isolated = 'martyna-tuckerman'
/
&ELECTRONS
conv_thr = 1.D-8,
mixing_beta = 0.7D0,
/
&IONS
/
ATOMIC_SPECIES
Ca 40.078 Ca.pbe-nsp-van.UPF
O 15.999 O.pbe-van_ak.UPF
ATOMIC_POSITIONS
Ca 0.0 0.0 0.0
O 0.5 0.5 0.5
K_POINTS Gamma
EOF
mpirun -np 40 -machinefile x1 /apps/codes/qe/6.4/bin/pw.x < ${a}.in > ${a}.out
done
done
My lattice constant is around 8 a.u , so I assumed the box size to be 3 times
of it. But when I run the script, the convergence was not achieved even after
100 iterations. Then I tried to take small box size of about 16 bohr. That too
didn't work. Then I even tried reducing ecutwfc and mixing_beta..but same error
was obtained. Can anyone suggest what can I do to resolve the issue?
Any kind of help is appreciated.
Thanks and regards.
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_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
users mailing list [email protected]
https://lists.quantum-espresso.org/mailman/listinfo/users
