[Pw_forum] input file for isolated atom
udayagiri sai babu
udayagiri3 at gmail.com
Fri Sep 11 11:17:57 CEST 2009
Dear prasenajit
thank you for your valuable inputs
On Fri, Sep 11, 2009 at 2:43 PM, Prasenjit Ghosh <prasenjit.jnc at gmail.com>wrote:
> For Ti atom, the electronic configuration is [*Ar*].*3d*2.*4s*2. So the
> magnetization should be 2.0 Bohr magneton due to the two electrons in the
> d-orbital, which is not what you are getting from your calculation.
>
> Also your smearing contribution is -0.00972779 Ry (about 0.1 eV), which I
> would say very high. If you would have find the correct magnetic ground
> state, then this should have been 0.0 Ry.
>
> As far as the bulk system is concerned, I'm not sure. It depends how Ti
> bulk behaves. You can search in the literature to find out what values of
> degauss other people have used.
>
> Mixing beta doesn't effect the energy of the system. It just helps you in
> convergence.
>
>
> Prasenjit.
>
> 2009/9/11 udayagiri sai babu <udayagiri3 at gmail.com>
>
>> 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.
>>
>>
>> _______________________________________________
>> 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.
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