[Pw_forum] Convergence NOT achieved for Sr2MnMoO6 using PAW pp

Shuai zhao-shuai at edu.life.kyutech.ac.jp
Sat Oct 10 05:00:40 CEST 2015


Dear Stefano and Pang,

Thank you very much for your advices.

I reduced to 10 atoms, then it converged well. But when I enlarged to 40 
atoms, it cannot converge with the same parameters of 10 atoms.

I then made a little change about the lattice parameters:

Sr   (0, 0, 0)                  -->  Sr   (0.25, 0.25, 0.25)
Mn  (0.25, 0.25, 0.25)   -->  Mn  (0, 0, 0)
Mo  (0.75, 0.25, 0.25)   -->  Mo  (0.5, 0, 0)
O    (0.25, 0.25, 0)        -->  O    (0.25, 0, 0)

and it can also converged well. What confused me is the difference 
between two lattice parameters is only a displacement, why causing the 
different convergence results?

Best regards,

Shuai Zhao

On 10/09/2015 04:43 PM, stefano de gironcoli wrote:
> I would give a shot to local-TF, mixing-beta not too small (~ 0.3).
>
> is it a metal ? does increasing degauss help ?
> is this an instability related to the occupation of the U-projectors ?
> does it converge if you if you remove U ?
> does the fcc cell with 10 atoms converge ?
>
> stefano
>
> On 09/10/2015 09:03, 庞瑞(PANG Rui) wrote:
>> Dear Zhao
>> The most efficient way is reducing the mixing_beta, you may try 0.1 
>> -0.01 or even smaller if you can afford the CPU time. Is 50 enough 
>> for O? You may check it, the smallest value usually is given in the 
>> PP file. A personal experience is that do not use semi-core PP. I do 
>> not understand the reason but I seldom get convergence when using 
>> semi-core PPs in periodical cases with PWSCF.
>> Good luck
>>
>>
>>
>>
>> ------------------
>>
>>
>>         庞瑞 (PANG Rui)
>>
>> South University of Science and Technology of China/Department of Physics
>>
>> No.1088,Xueyuan Road, Shenzhen,Guangdong
>>
>> ------------------ Original ------------------
>> *From: * "Shuai"<zhao-shuai at edu.life.kyutech.ac.jp>;
>> *Date: * Fri, Oct 9, 2015 12:00 PM
>> *To: * "PWSCF Forum"<pw_forum at pwscf.org>;
>> *Subject: * [Pw_forum] Convergence NOT achieved for Sr2MnMoO6 using 
>> PAW pp
>> Dear User:
>>
>> I am doing the SCF calculation of Sr2MnMoO6 using PAW Potentials but it
>> cannot converged.
>>
>> I checked different Ecut (30Ry, 40Ry or 50Ry), mixing mode (TF or
>> plain), diagonalization (david or cg) and mixing_beta (0.3, 0.7), but it
>> always not converged.
>>
>> The SCF input is:
>>
>>   &control
>>    calculation   = 'scf'
>>    prefix           = 'Sr2MnMoO6'
>>    restart_mode  = 'from_scratch'
>>    pseudo_dir    = '/'
>>    outdir           = '/'
>>   /
>>   &system
>>    ibrav            = 1
>>    celldm(1)     = 15.27295
>>    nat               = 40
>>    ntyp             = 4
>>    ecutwfc        = 50
>>    ecutrho        = 600
>>    occupations   = 'smearing'
>>    smearing      = 'mp'
>>    degauss        = 0.01
>>    lda_plus_u     = .true.
>>    Hubbard_U(2)  = 4.0
>>   /
>>   &electrons
>>    conv_thr         = 1e-8
>>    mixing_mode   = 'TF'
>>    mixing_beta   = 0.7
>>    diagonalization = 'david'
>>   /
>> ATOMIC_SPECIES
>>    Sr    87.620   Sr.pbe-spn-kjpaw_psl.1.0.0.UPF
>>    Mn   54.938   Mn.pbe-spn-kjpaw_psl.1.0.0.UPF
>>    Mo   95.960   Mo.pbe-spn-kjpaw_psl.1.0.0.UPF
>>    O     15.999   O.pbe-n-kjpaw_psl.1.0.0.UPF
>> ATOMIC_POSITIONS (crystal)
>>    Sr    0.0000   0.0000   0.0000
>>    Sr    0.5000   0.0000   0.0000
>>    Sr    0.0000   0.5000   0.0000
>>    Sr    0.5000   0.5000   0.0000
>>    Sr    0.0000   0.0000   0.5000
>>    Sr    0.5000   0.0000   0.5000
>>    Sr    0.0000   0.5000   0.5000
>>    Sr    0.5000   0.5000   0.5000
>>    Mn   0.2500   0.2500   0.2500
>>    Mo   0.7500   0.2500   0.2500
>>    Mo   0.2500   0.7500   0.2500
>>    Mn   0.7500   0.7500   0.2500
>>    Mo   0.2500   0.2500   0.7500
>>    Mn   0.7500   0.2500   0.7500
>>    Mn   0.2500   0.7500   0.7500
>>    Mo   0.7500   0.7500   0.7500
>>    O     0.2500  -0.0140   0.2500
>>    O    -0.0140   0.2500   0.2500
>>    O     0.2500   0.2500  -0.0140
>>    O     0.7500   0.0140   0.2500
>>    O     0.5140   0.2500   0.2500
>>    O     0.7500   0.2500   0.0140
>>    O     0.2500   0.5140   0.2500
>>    O     0.0140   0.7500   0.2500
>>    O     0.2500   0.7500   0.0140
>>    O     0.7500   0.4860   0.2500
>>    O     0.4860   0.7500   0.2500
>>    O     0.7500   0.7500  -0.0140
>>    O     0.2500   0.0140   0.7500
>>    O     0.0140   0.2500   0.7500
>>    O     0.2500   0.2500   0.5140
>>    O     0.7500  -0.0140   0.7500
>>    O     0.4860   0.2500   0.7500
>>    O     0.7500   0.2500   0.4860
>>    O     0.2500   0.4860   0.7500
>>    O    -0.0140   0.7500   0.7500
>>    O     0.2500   0.7500   0.4860
>>    O     0.7500   0.5140   0.7500
>>    O     0.5140   0.7500   0.7500
>>    O     0.7500   0.7500   0.5140
>> K_POINTS (automatic)
>>    4 4 4 1 1 1
>>
>> Thanks in advance for your suggestions.
>>
>> Best regards,
>>
>> Shuai Zhao
>>
>> -- 
>> PhD candidate
>> Graduate School of Life Science and Systems Engineering
>> Kyushu Institute of Technology, Japan
>>
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-- 
PhD candidate
Graduate School of Life Science and Systems Engineering
Kyushu Institute of Technology, Japan

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