[QE-users] Energy of isolated atom of CaO

[Pooja Vyas]

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.
>
>
>
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