[QE-users] Energy of isolated atom of CaO

[Malathe Khalil]

Dear Pooja
I am not expert but I am suggesting to add this line electron_maxstep = 500
*Under *&ELECTRONS

Try and see if it works
500 is just from my mind you can put any number.  Because the default is
100.

Thanks
Malathe

On Sat, 27 Jun 2020, 1:56 pm Pooja Vyas, <poojavyas595 at gmail.com> wrote:

> 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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>
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