[QE-users] Energy of isolated atom of CaO

[Pooja Vyas]

Please let me know if this is the correct way to get isolated energies or
not. Does input script require any modifications?
Thanks.

On Sat, Jun 27, 2020 at 4:55 PM Pooja Vyas <poojavyas595 at gmail.com> wrote:

> The other way I tried computing isolated energy of Ca and O, is using the
> following separate inputs for Ca and O. Are the input scripts valid? The
> energies got converged for the following scripts.
>
> On Sat, Jun 27, 2020 at 4:45 PM Pietro Delugas <pdelugas at sissa.it> wrote:
>
>> 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 <https://go.microsoft.com/fwlink/?LinkId=550986> for
>> Windows 10
>>
>>
>>
>> *From: *Pooja Vyas <poojavyas595 at gmail.com>
>> *Sent: *Saturday, June 27, 2020 11:56 AM
>> *To: *Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>
>> *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 <pdelugas at sissa.it>
>> 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 <https://go.microsoft.com/fwlink/?LinkId=550986> for
>> Windows 10
>>
>>
>>
>> *From: *Pooja Vyas <poojavyas595 at gmail.com>
>> *Sent: *Friday, June 26, 2020 8:12 AM
>> *To: *Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>
>> *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.
>>
>>
>>
>> _______________________________________________
>> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
>> users mailing list users at lists.quantum-espresso.org
>> https://lists.quantum-espresso.org/mailman/listinfo/users
>>
>>
>> _______________________________________________
>> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
>> users mailing list users at lists.quantum-espresso.org
>> https://lists.quantum-espresso.org/mailman/listinfo/users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20200627/cc93ac9b/attachment.html>