[Pw_forum] Problem with normal modes of NO gas phase

[Paolo Giannozzi]

The last part of this message:
https://www.mail-archive.com/pw_forum@pwscf.org/msg33028.html
may be of interest for you. I also remember hard-to-converge phonons with
some pseudopotentials, both ultrasoft (notably old Vanderbilt USPP) and
norm-conserving (N and O may be very hard)

Paolo

On Thu, Nov 16, 2017 at 10:09 AM, Francesco Moriggi <frank7793 at live.it>
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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>



-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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