[Pw_forum] Problem with normal modes of NO gas phase

[Francesco Moriggi]

Thank you very much for the help!
Last question: are these advices valid to do adsorbed-NO on TiO2 
surfaces calculations?

Best regards,

Francesco Moriggi


Il 20/11/2017 21:18, Nicola Marzari ha scritto:
>
>
> Dear Francesco,
>
>
> to follow up on Paolo's advice, I would do this:
>
> 1) freeze the molecule - i.e. do not relax it.
>
> 2) tighten the 2 thresholds a lot -  conv_thr
> and tr2_ph (i.e. make them smaller by one order of magnitude, two, 
> etc...).
>
> 3) use sssp pseudos: http://materialscloud.org/sssp/
>
> The tables show exactly what is the convergence of the phonons with
> cutoff (for molecular solids in the case of N and O),
> using the scripts from
>
> http://materialscloud.org/sssp/downloads.html
>
> where you can find all the parameters we used
>
> 4) once you feel you are in control on the cutoffs and tolerance 
> thresholds, you can start relaxing the molecule. In order to get
> very accurate results there, you need to have a very tight criterion on
> the relaxation, as well.
>
>                 nicola
>
>
>
> On 16/11/2017 10:09, Francesco Moriggi wrote:
>> Hello, i'm Francesco Moriggi, a master student at the Milan 
>> University, i have a problem with ph.x. I am calculating NO frequency 
>> and i'm not reaching a convergence in values compared to cutoff 
>> energy, using norm conserving and ultrasoft pseudopotentials. Values 
>> i get are (i've put an image too in the email):
>>
>> *Cutoff   freq Norm    freq US*
>>
>> **
>>
>> *75        1879.0        1844.4*
>>
>> **
>>
>> *80        1875.5        1858.2*
>>
>> **
>>
>> *85        1890.6        1907.1*
>>
>> **
>>
>> *90        1923.5        1895.2*
>>
>> **
>>
>> *100      1889.6        1909.3*
>>
>> **
>>
>> *110      1914.2        1893.1*
>>
>> **
>>
>> *120      1890.5       1900.4*
>>
>> **
>>
>> *130       1890.7        1901.0*
>>
>> **
>>
>> *140        1914.7        1890.9*
>>
>> **
>>
>> *150        1886.9        ////*
>>
>> With Gaussian (aug-cc-pv5Z) i've got *1889.21* cm-1.
>>
>> An example of the input of geometry optimization is:
>>
>> *&CONTROL**
>> **  calculation  = "relax",**
>> **  prefix       = "NO",**
>> **  pseudo_dir   = 
>> "/galileo/home/userexternal/fmoriggi/QE/NO/pseudoNO/ultrasoft",**
>> **  outdir       = "./out",**
>> **/**
>> **&SYSTEM**
>> **  ibrav     = 1,**
>> **  a         = 20,**
>> **  nat       = 2,**
>> **  ntyp      = 2,**
>> **  nspin     = 2,**
>> **  ecutwfc   = 150.D0,**
>> **  ecutrho = 1200.D0,**
>> **  occupations = 'smearing', smearing = 'gauss', degauss=0.02,**
>> **  starting_magnetization(1)=-0.9,**
>> **  starting_magnetization(2)=1.5,**
>> **/**
>> **&ELECTRONS**
>> **  electron_maxstep = 500,**
>> **  conv_thr    = 1.D-7,**
>> **  mixing_beta = 0.7D0,**
>> **/**
>> **&IONS**
>> **/**
>> **ATOMIC_SPECIES**
>> **O  16.00 O.pbe-van_ak.UPF**
>> **N  14.00 N.pbe-van_ak.UPF**
>> **ATOMIC_POSITIONS {angstrom}**
>> **N  1.16 0.0  0.0**
>> **O  0.000  0.0  0.0  0 0 0**
>> **K_POINTS**
>> **1**
>> **0.0 0.0 0.0 1.0*
>>
>> Later i've done an scf  with a better conv_thr. This is the input.
>>
>> *&CONTROL**
>> **  calculation  = "scf",**
>> **  prefix       = "150",**
>> **  pseudo_dir   = 
>> "/galileo/home/userexternal/fmoriggi/QE/NO/pseudoNO/ultrasoft",**
>> **  outdir       = "./out150",**
>> **/**
>> **&SYSTEM**
>> **  ibrav     = 1,**
>> **  a         = 20,**
>> **  nat       = 2,**
>> **  ntyp      = 2,**
>> **  nspin     = 2,**
>> **  ecutwfc   = 150.D0,**
>> **  ecutrho   = 1200.D0,**
>> **  occupations = 'smearing', smearing = 'gauss', degauss=0.02,**
>> **  starting_magnetization(1)=-0.9,**
>> **  starting_magnetization(2)=1.5,**
>> **/**
>> **&ELECTRONS**
>> **  electron_maxstep = 500,**
>> **  conv_thr    = 1.D-9,**
>> **  mixing_beta = 0.7D0,**
>> **/**
>> **&IONS**
>> **/**
>> **ATOMIC_SPECIES**
>> **O  16.00 O.pbe-van_ak.UPF**
>> **N  14.00 N.pbe-van_ak.UPF**
>> **ATOMIC_POSITIONS {angstrom}**
>> **N  1.166278 0.0  0.0**
>> **O  0.000  0.0  0.0  0 0 0**
>> **K_POINTS**
>> **1**
>> **0.0 0.0 0.0 1.0*
>>
>> And then i run the ph.x with this input:
>>
>> *phonon calculation - NO**
>> ** &inputph**
>> **  tr2_ph=4.0d-12,**
>> **  prefix='150'**
>> **  amass(1)=14.007,**
>> **  amass(2)=15.9994,**
>> ** 
>> outdir='/galileo/home/userexternal/fmoriggi/QE/NO/relax/ultra/out150'**
>> ** /**
>> ** 0.0 0.0 0.0*
>>
>> If you can help me it would be very useful to my future TiO2 based 
>> calculations.
>>
>>
>> Best regards,
>>
>> Francesco Moriggi
>>
>> Webpage: http://users.unimi.it/ceotto/about_FrancescoMoriggi.html
>>
>>
>>
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>
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