[Pw_forum] Force is fluctuating for water system

Narendranath Ghosh ghosh.naren13 at gmail.com
Fri Dec 22 18:57:03 CET 2017


Dear Lorenzo , Dear Seitsonen Thank you very much. Actually what I am
trying to find is to Where do the excess e- prefer to stay in my water
system ?

I have crossed 50 BFGS steps but still it could not  find the minimum.
The Force is fluctuating very much .I have applied 90 Ry with a pseudo
potential and used BLYP exchange-correlation functional from a standard
reference. (THE JOURNAL OF CHEMICAL PHYSICS 128, 214506 2008)
 any other factor that should care relaxing a system with odd number of
electrons.

*Dr. Narendra Nath Ghosh*

*Research Associate*

*University of Gour  Banga*

*Malda-732102*

*India*

*Phone No : 09126667601*


On Fri, Dec 22, 2017 at 2:07 AM, Ari P Seitsonen <Ari.P.Seitsonen at iki.fi>
wrote:

>
> Dear Narendra Nath Ghosh,
>
>   Adding to Lorenzo's answer, a small note: You seem to have an odd number
> of electrons but you do not specify 'nspin = 2' - are you sure that this is
> what you intended to do (physically)? 70 Ry with a pseudo potential à la
> Troullier-Martins for oxygen, it might be at the lower limit (it depends on
> the core radii, usually I would go for 80-90 Ry minimum). And, do you know
> if the electron gets localised or remains delocalised - this is an open
> question to my knowledge, and might well depend on the kind of
> exchange-correlation functional used (GGA like BLYP probably delocalise it
> - with the highest occupied orbital in the conduction band - and hybrid
> functionals might localise it).
>
>     Greetings from Helsinki/Finland,
>
>        apsi
>
> -=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=
> -=*=-=*=-=*=-=*=-
>   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
>     Ecole Normale Supérieure (ENS), Département de Chimie, Paris
>     Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935
>
>
>
> On Tue, 19 Dec 2017, Narendranath Ghosh wrote:
>
> Dear all
>>
>> I am relaxing a system of 128 water molecule with extra electron.The
>> force is fluctuating even after bfgs
>> steps   =  48.
>>
>>
>>
>> Input:
>>
>> &CONTROL
>>   calculation='relax',
>>   outdir='/share_home/hpc/NEGATIVE_HYDRATED_ELECTRON/OUTPUT',
>>   prefix='water-128-negative',
>>   pseudo_dir='/share_home/hpc/RESEARCH_SCHOLAR/HYDRATED-ELECTRON/pseudo',
>>   verbosity='high',
>>   restart_mode='restart',
>> /
>> &SYSTEM
>>   ibrav=0,
>>   celldm(1)=29.8576727681d0,
>>   nat=384,
>>   tot_charge=-1,
>>   ntyp=2,
>>   ecutwfc=70,
>>   ecutrho=280,
>>   input_dft='BLYP',
>>   occupations='smearing',
>>   degauss=0.05d0,
>> /
>> &ELECTRONS
>>   mixing_beta=0.500d0,
>>   electron_maxstep=500,
>> /
>> &IONS
>> /
>> ATOMIC_SPECIES
>>  O  16.0d0   O.blyp-mt.UPF
>>  H  1.0079d0 H.blyp-vbc.UPF
>>
>> K_POINTS {automatic}
>>   1 1 1 0 0 0
>> CELL_PARAMETERS {alat}
>>   1.000000000000d0  0.000000000000d0  0.000000000000d0
>>   0.000000000000d0  1.000000000000d0  0.000000000000d0
>>   0.000000000000d0  0.000000000000d0  1.000000000000d0
>>
>> Output
>>
>>     Total force =     0.030447     Total SCF correction =     0.001115
>>      Total force =     0.033732     Total SCF correction =     0.000223
>>      Total force =     0.042921     Total SCF correction =     0.000171
>>      Total force =     0.032971     Total SCF correction =     0.000165
>>      Total force =     0.032983     Total SCF correction =     0.000266
>>      Total force =     0.036132     Total SCF correction =     0.000252
>>        Total force =     0.040191     Total SCF correction =     0.000833
>>      Total force =     0.032897     Total SCF correction =     0.001663
>>      Total force =     0.025425     Total SCF correction =     0.000288
>>      Total force =     0.019869     Total SCF correction =     0.000279
>>      Total force =     0.020382     Total SCF correction =     0.000102
>>      Total force =     0.025164     Total SCF correction =     0.000109
>>      Total force =     0.027580     Total SCF correction =     0.000141
>>      Total force =     0.026211     Total SCF correction =     0.000188
>>      Total force =     0.023574     Total SCF correction =     0.000139
>>      Total force =     0.024877     Total SCF correction =     0.000103
>>      Total force =     0.027597     Total SCF correction =     0.000131
>>      Total force =     0.027563     Total SCF correction =     0.000169
>>      Total force =     0.023015     Total SCF correction =     0.000195
>>      Total force =     0.021111     Total SCF correction =     0.000109
>>      Total force =     0.021345     Total SCF correction =     0.000092
>>      Total force =     0.023793     Total SCF correction =     0.000129
>>      Total force =     0.024400     Total SCF correction =     0.000145
>>      Total force =     0.025073     Total SCF correction =     0.000243
>>      Total force =     0.022300     Total SCF correction =     0.000376
>>      Total force =     0.020060     Total SCF correction =     0.000097
>>      Total force =     0.021991     Total SCF correction =     0.000134
>>      Total force =     0.022541     Total SCF correction =     0.000132
>>      Total force =     0.023051     Total SCF correction =     0.000158
>>      Total force =     0.023734     Total SCF correction =     0.000168
>>
>>
>>      Total force =     0.023734     Total SCF correction =     0.000168
>>      number of scf cycles    =  49
>>      number of bfgs steps    =  48
>>      energy   old            =   -4400.3520443575 Ry
>>      energy   new            =   -4400.3528674259 Ry
>>      CASE: energy  _new < energy  _old
>>      new trust radius        =       0.0602516409 bohr
>>      new conv_thr            =       0.0000000591 Ry
>>
>> Please help me.
>>
>> Dr. Narendra Nath Ghosh
>>
>> Research Associate
>>
>> University of Gour  Banga
>>
>> Malda-732102
>>
>> India
>>
>> Phone No : 09126667601
>>
>>
>>
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