[Pw_forum] input file for isolated atom

[udayagiri sai babu]

Dear prasenajit this is the part of my output for the posted input file.
(smearing contribution is there! though it is small ) is the degauss value
too high for isolated atom or it is high for bulk calculation also? because
i use around 0.01 Ry value for all my calculations. Does the mixing beta
value effect the energy of the system?

    one-electron contribution =  -155.91791626 Ry
     hartree contribution      =    74.49216944 Ry
     xc contribution           =   -14.37611953 Ry
     ewald contribution        =   -20.42854186 Ry
     smearing contrib. (-TS)   =    -0.00972779 Ry

     total magnetization       =     3.24 Bohr mag/cell
     absolute magnetization    =     3.24 Bohr mag/cell

     convergence has been achieved in  34 iterations

On Fri, Sep 11, 2009 at 2:06 PM, Prasenjit Ghosh <prasenjit.jnc at gmail.com>wrote:

> Dear Udayagiri,
>
> First of all it's not clear whether you have any question other than
> whether your input file is correct.
>
> Now some comments about your input file:
>
> (a) while doing calculations for any zero dimensions you should always set
> nosym =.true.
> (b) Your value of degauss is too high.....you should use some value around
> 0.001 Ry. According to my experience, doing cal. for a single atom is
> tricky, specially when you are using a smearing. Even that doesn't confirm
> you will get the correct ground state for the atom. So what you should do is
> at the end of the calculation check the values of the total magnetization,
> absolute magnetization and the smearing contribution. The last term should
> be exactly zero.
> (c) You don't need to set tstress and tprnfor true.
> (c) mixing_beta= 0.7 too large.....I would put something smaller....0.3
> (d) I hope you have checked the convergence of ecut rho & ecutwfc.
>
> Prasenjit.
>
> 2009/9/11 udayagiri sai babu <udayagiri3 at gmail.com>
>
>> Hi everybody
>> I want to calculate the cohesive energy of Titanium for that i need to
>> calculate the energy of an isolated atom previously in the forum somebody
>> has suggested me to do spin polarisation calculation for the isolated atom.
>> I have written an input file accordingly some one can see and tell me if my
>> input script is true. I have read the forum archives on this topic but they
>> are not exactly answering my question. Can somebody please help me.
>> *
>> Input file for isolated atom *
>>
>> &control
>> calculation = 'scf',
>> restart_mode='from_scratch',
>> outdir='/home/sai/temp',
>> prefix='titanium'
>> pseudo_dir='/home/sai/softwares/espresso-4.0.1/pseudo/',
>> tstress = .TRUE.,
>> tprnfor = .TRUE.,
>> /
>> &system
>> ibrav=1
>> celldm(1)=20,
>> nat=1,
>> ntyp=1
>> ecutwfc=25,
>> ecutrho=250,
>> occupations='smearing',
>> smearing='mv',
>> degauss=0.010000
>> nspin=2
>> starting_magnetization(1)=0.2
>> /
>> &electrons
>> conv_thr=1.D-8,
>> diagonalization='david',
>> mixing_mode='plain',
>> mixing_beta= 0.7,
>> /
>> ATOMIC_SPECIES
>> Ti  47.867  Ti.pbe-sp-van_ak.UPF
>> ATOMIC_POSITIONS (crystal)
>> Ti     0.00000000    0.00000000    0.00000000
>> K_POINTS GAMMA
>>
>> --
>> U.Saibabu
>> PhD student,
>> Deformation mechanisms modeling group,
>> Materials engineering department,
>> IISc Bangalore,
>> India.
>>
>>
>> _______________________________________________
>> Pw_forum mailing list
>> Pw_forum at pwscf.org
>> http://www.democritos.it/mailman/listinfo/pw_forum
>>
>>
>
>
> --
> PRASENJIT GHOSH,
> POST-DOC,
> ROOM NO: 265, MAIN BUILDING,
> CM SECTION, ICTP,
> STRADA COSTERIA 11,
> TRIESTE, 34104,
> ITALY
> PHONE: +39 040 2240 369 (O)
>              +39 3807528672 (M)
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
>


-- 
U.Saibabu
PhD student,
Deformation mechanisms modeling group,
Materials engineering department,
IISc Bangalore,
India.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20090911/70352d34/attachment.html>