[Pw_forum] very high pressure in scf

Fri May 27 12:00:33 CEST 2011

dear Sanjeev Gupta
    I think you should find what is wrong with your input.
    my suggestion is to read the documentation of Abinit and QE and 
understand each variable you are setting and how they translate betwenn 
the codes.
    there used to be an input translator between the two codes that may 
still work although has not been used extensively (look in to qe-forge 
->quantum espresso ->files ->QE-ABINIT converter)
    it may help to take a simpler system where you have less variable to 
test and the incrementally  add complexity
    good luck

stefano

On 05/27/2011 06:19 AM, Sanjeev Gupta wrote:
> Dear Sir,
>
> Thank you for kind reply.
>
> Here i am attaching the input file of ABINIT which gives less pressure for
> same structure as i have taken in PWSCF (I mentioned in my previous mail).
> Please look in this matter and suggest me.
>
>
> #********** input file from abinit code......
>
> ndtset     1
> acell       5.30  5.30  19.65615823
> dilatmx   1.02
> toldfe      1.0d-6
> #Common data****************
> ixc         11
> kptopt    1
> nshiftk   1
> shiftk     0.0  0.0  0.5
> ngkpt     6 6 6
> ecut       30
> ecutsm  0.5
> ntime     50
> iscf       7
> nstep    50
> nband   32
> angdeg 90  90  120
> spgroup 166
> brvltt     0
> occopt   3
> tsmear   0.01
> natom    9
> typat      1 2 2 1 2 2 1 2 2
> ntypat     2
> znucl      26 7
>   xred
>   -1.8503717077E-17 -1.8503717077E-17 -1.8503717077E-17
>   ...........
> ............
> ...........
>    3.3333333333E-01  6.6666666667E-01  2.2599217437E-01
> chkprim 0
>
>
>
>
> #****************************************************************************
>
> 1,1           Top
>
>
> On Fri, May 27, 2011 at 1:16 AM, Stefano de Gironcoli<degironc at sissa.it>wrote:
>
>>   I think the two structures are not the same, or some of the parameters
>> have non equivalent
>> values.
>> stefano
>>
>>
>> On 05/26/2011 08:50 PM, Sanjeev Gupta wrote:
>>
>> Dear Sir,
>> Thanks for reply.
>>
>>
>> On Thu, May 26, 2011 at 10:23 PM, Stefano de Gironcoli<degironc at sissa.it>  <degironc at sissa.it>wrote:
>>
>>
>>    with this input the Fe-N distance is some 1.2 A... I'm pretty sure it
>> cannot be the intended structure
>> Are you sure the system is not in crystal coordinate ?
>>   stefano
>>
>>
>>   Yes, its true that  while looking from xcrysden particularly the bond
>> lengths between the Fe-N and N-N  but i am very surprised why both ABINIT
>> and PWSCF code gives such vast Difference in calculated Pressure for the
>> identical geometry which is not cleared yet. Here the bond lenth Fe-N is
>> ~1.24Ang.
>> Please Suggest More.
>>
>>
>>
>>
>>       On 05/26/2011 04:13 PM, Sanjeev Gupta wrote:
>>
>> Dear Maxim
>>
>> Thank for kind reply.
>>
>> My unit cell is as same in ABINIT  as in pwscf in Bohr  unit. In addition I
>> am using the spacegroup 166   (R3(bar)M) space group with conventional unit
>> cell rather than primitive unit cell the lattice parameter is taken as below
>> 1. for abinit
>>
>> a=5.359168252 Bohr
>> b=5.359168252 Bohr
>> c=20.08294707 Bohr
>>
>> 2. for PWSCF
>>
>> ibrav=4,
>> celldm(1) = 5.359168242 Bohr
>> celldm(3) = 3.7474
>>
>> Part of my input file is :
>>
>> PWSCF
>>
>> &control
>>      calculation = 'scf'
>>      prefix='FeN2',
>>      restart_mode='from_scratch',
>>      outdir='./'
>>      pseudo_dir = '/',
>>      tstress = .true.
>>      tprnfor = .true.
>>      etot_conv_thr = 1.0d-5,
>>      forc_conv_thr = 1.0d-4,
>>   /
>>   &system
>>      ibrav=4,
>>      celldm(1) = 5.359168242,
>>      celldm(3) = 3.7474
>>      nat=9,
>>      ntyp=2,
>>      nosym =.true.,
>>      ecutwfc = 20,
>>      ecutrho=200,
>>      occupations='smearing',
>>      smearing='m-p',
>>      degauss=0.001,
>>   /
>>   &electrons
>>       mixing_mode     = "local-TF",
>>       mixing_beta     =  0.700000,
>>       conv_thr        =  1.0d-10,
>> /
>> ATOMIC_SPECIES
>> Fe  55.845  Fe.pbe-sp-van.UPF
>> N   14.0067 N.pbe-van_ak.UPF
>> ATOMIC_POSITIONS
>> Fe    -1.8503717077E-17 -1.8503717077E-17 -1.8503717077E-17
>> N     -1.8503717077E-17 -1.8503717077E-17  4.4000000000E-01
>>
>> ..............................
>> ............
>>
>> N      3.3333333333E-01  6.6666666667E-01  2.2666666667E-01
>> K_POINTS automatic
>> 6 6 6 0 0 0
>>
>>
>> Best Regards
>>
>>
>> Sanjay D. Gupta
>> Research Fellow
>> Department of Physics,
>> Bhavnagar University, Bhavnagar-364 022
>> Gujarat, Mobile-9879666643email:guptasanjay_56 at yahoo.co.in
>>
>>
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