The ABINIT Users Mailing List ( CLOSED )

[Xavier Gonze <xavier.gonze@uclouvain.be>]

Dear Shelleny,

You should have a look at

 Lattice properties of  PbX (X=S, Se, Te) : experimental studies and  
ab initio calculations including spin-orbit effects

A.H. Romero, M. Cardona, R.K. Kremer, R. Lauck, G. Siegle, J. Serrano,  
X. Gonze

Phys. Rev. B 78, 224302 (2008)

and related publications...

X.

On 24 Jul 2009, at 04:18, 徐 wrote:

> Dear Josef,
> Many thanks for your help. I've also calculated the material using  
> LDA HGH pesudopotentials with ecut 70 and ngkpt 3*4. And the  
> negative acoustic frequency can't be summed to zero by anaddb. Does  
> that because of not enough ngkpt or not including semi core states  
> in the pesudopotential files?
> Thank you in advance.
> Best regards,
> shelleny
>
> > From: Josef Zwanziger
>
> > Reply-To:
> > To: 徐
>
> > Subject: Re: [abinit-forum] negative Phonon frequency at gamma and  
> > wrong PHDOS
> > Date:Thu, 23 Jul 2009 07:26:00 -0300
> >
> > The small negative values are due to symmetry breaking of your finite
> > k coverage and are fixed by the acoustic sum rule in anaddb. The  
> > forum
> > lists have this point discussed many times. Also, you will almost
> > surely need semi core d states in the Pb pseudo and possibly also the
> > Te pseudo.
> >
> > wrote:
> > >  Dear forum users,
> > > I'm following tutor of RF2 and calculating phonon dispersion curve  
> > > and PDOS
> > > for PbTe. The psudopotential files are 82pb.pspnc and  
> > > 52te.pspnc(LDA), ecut
> > > 30, ngkpt 3*4.  The curious thing is that abinit gave out  
> > > negative  Phonon
> > > energy and frequency in the output file as following;
> > >
> > > Phonon wavevector (reduced coordinates) :  0.00000  0.00000  0.00000
> > > Phonon energies in Hartree :
> > >  -2.656610E-07 -2.656575E-07 -2.656473E-07  2.114512E-04   
> > > 2.114512E-04
> > >   2.114512E-04
> > >
> > > But after analyzed ddb anaddb gave out zero Phonon energy and  
> > > frequency at
> > > gamma.
> > >
> > >  Phonon at Gamma, with non-analyticity in the
> > >  direction (cartesian coordinates)  1.00000  0.00000  0.00000
> > > Phonon energies in Hartree :
> > >   0.000000E+00  0.000000E+00  0.000000E+00  2.114513E-04   
> > > 2.114514E-04
> > >   4.680436E-04
> > > Phonon frequencies in cm-1    :
> > > -  0.000000E+00  0.000000E+00  0.000000E+00  4.640819E+01   
> > > 4.640822E+01
> > > -  1.027237E+02
> > >
> > > Is it natural or not?
> > > What's more, I use prtdos 1 to print the PDOS. But the output  
> > > PHDOS has
> > > omiga from -0.29933    to 17.18245  and the total distribution  
> > > isn't right.
> > > Is there anything wrong?
> > > The two input files are as following. Any comments will be  
> > > appreciated.
> > > Thank you in advance.
> > >
> > > Best regards,
> > > shelleny
> > >
> > > #####abinis input file:#####################
> > > ndtset 10
> > > #Datasets 1 : GS
> > > getwfk1 0
> > > kptopt1 1
> > > nqpt1 0
> > > tolvrs1 1.0d-18
> > > rfphon1 0
> > > #q vectors
> > > nqpt 1
> > >     qpt2   0.00000000E+00  0.00000000E+00  0.00000000E+00
> > >     qpt3   0.00000000E+00  0.00000000E+00  0.00000000E+00
> > >     qpt4   2.50000000E-01  0.00000000E+00  0.00000000E+00
> > >     qpt5   5.00000000E-01  0.00000000E+00  0.00000000E+00
> > >     qpt6   2.50000000E-01  2.50000000E-01  0.00000000E+00
> > >     qpt7   5.00000000E-01  2.50000000E-01  0.00000000E+00
> > >     qpt8  -2.50000000E-01  2.50000000E-01  0.00000000E+00
> > >     qpt9   5.00000000E-01  5.00000000E-01  0.00000000E+00
> > >     qpt10 -2.50000000E-01  5.00000000E-01  2.50000000E-01
> > > #Dataset 2 : ddk
> > > rfelfd2   2
> > > rfphon2   0
> > > kptopt2   2
> > > iscf2     -3
> > > tolvrs2 0.0
> > > tolwfr2 1.0d-22
> > > #Dataset 3: electric field + phonon response at gamma
> > > rfelfd3  3
> > > getddk3  -1
> > > kptopt3   2
> > > #Dataset 4-74: phonon perturb
> > > getwfk 1
> > > kptopt 3
> > > rfphon 1
> > > rfatpol 1 2
> > > rfdir 1 1 1
> > > tolvrs 1.0d-8
> > > # non-spinor wavefunctions, without SO coupling
> > > nband   5
> > > #Common data
> > > acell 3*4.5672  Angstroms
> > > angdeg 60 60 60
> > > chkprim 0
> > > ecut  30
> > > natom  2
> > > ntypat  2
> > > typat  1 2
> > > xred    3*0.0d0
> > >         3*0.5d0
> > > znucl 82 52
> > > #Kpt grid
> > > ngkpt 3*4
> > > nshiftk 4
> > > shiftk 0.5 0.5 0.5
> > >       0.5 0   0
> > >       0   0.5 0
> > >       0   0   0.5
> > > #SCF
> > > iscf  5
> > > diemac 10
> > > nstep    100
> > >
> > >
> > > ######anaddb  input file#########################
> > > !Flags
> > > dieflag   1     ! Frequency-dependent Dielectric tensor flag
> > > ifcflag   1     ! Interatomic force constant flag
> > > thmflag   1     ! Thermodynamical properties flag
> > > !Wavevector grid number 1 (coarse grid, from DDB)
> > >  brav    1      ! Bravais Lattice : 1-S.C., 2-F.C., 3-B.C., 4-Hex.)
> > >  ngqpt   4  4  4   ! Monkhorst-Pack indices
> > >  nqshft  1         ! number of q-points in repeated basic q-cell
> > >  q1shft  3*0.0
> > > !Effective charges
> > >     asr   1     ! Acoustic Sum Rule. 1 => imposed asymetrically
> > >  chneut   1     ! Charge neutrality requirement for effective  
> > > charges.
> > > !Interatomic force constant info
> > >  dipdip  1      ! Dipole-dipole interaction treatment
> > >  ifcana  1      ! Analysis of the IFCs
> > >  ifcout 16      ! Number of IFC's written in the output, per atom
> > >  natifc  2      ! Number of atoms in the cell for which ifc's are  
> > > analysed
> > >   atifc  1 2    ! List of atoms
> > > !Phonon band structure output for band2eps - See note near end for
> > > ! dealing with gamma LO-TO splitting issue.
> > >   eivec  4
> > >   prtdos 1
> > > !Wavevector list number 1 (Reduced coordinates and normalization  
> > > factor)
> > >
> > >  nph1l    41      ! number of phonons in list 1
> > >
> > >  qph1l   0.5000  0.5000  0.5000   1.0    !(L point)
> > >          0.5500  0.5500  0.5500   1.0
> > >          0.6000  0.6000  0.6000   1.0
> > >          0.6500  0.6500  0.6500   1.0
> > >          0.7000  0.7000  0.7000   1.0
> > >          0.7500  0.7500  0.7500   1.0
> > >          0.8000  0.8000  0.8000   1.0
> > >          0.8500  0.8500  0.8500   1.0
> > >          0.9000  0.9000  0.9000   1.0
> > >          0.9500  0.9500  0.9500   1.0
> > >          1.0000  1.0000  1.0000   1.0    !(gamma point)
> > >          0.9500  0.9500  1.0000   1.0
> > >          0.9000  0.9000  1.0000   1.0
> > >          0.8500  0.8500  1.0000   1.0
> > >          0.8000  0.8000  1.0000   1.0
> > >          0.7500  0.7500  1.0000   1.0
> > >          0.7000  0.7000  1.0000   1.0
> > >          0.6500  0.6500  1.0000   1.0
> > >          0.6000  0.6000  1.0000   1.0
> > >          0.5500  0.5500  1.0000   1.0
> > >          0.5000  0.5000  1.0000   1.0    !(X point)
> > >          0.4875  0.4875  0.9750   1.0
> > >          0.4750  0.4750  0.9500   1.0
> > >          0.4625  0.4625  0.9250   1.0
> > >          0.4500  0.4500  0.9000   1.0
> > >          0.4375  0.4375  0.8750   1.0
> > >          0.4250  0.4250  0.8500   1.0
> > >          0.4125  0.4125  0.8250   1.0
> > >          0.4000  0.4000  0.8000   1.0
> > >          0.3875  0.3875  0.7750   1.0
> > >          0.3750  0.3750  0.7500   1.0    !(K point)
> > >          0.3375  0.3375  0.6750   1.0
> > >          0.3000  0.3000  0.6000   1.0
> > >          0.2625  0.2625  0.5250   1.0
> > >          0.2250  0.2250  0.4500   1.0
> > >          0.1875  0.1875  0.3750   1.0
> > >          0.1500  0.1500  0.3000   1.0
> > >          0.1125  0.1125  0.2250   1.0
> > >          0.0750  0.0750  0.1500   1.0
> > >          0.0375  0.0375  0.0750   1.0
> > >          0.0000  0.0000  0.0000   1.0    !(gamma point)
> > >
> > > !Wavevector list number 2 (Cartesian directions for non-analytic  
> > > gamma
> > > phonons)
> > >  nph2l    1       ! number of directions in list 2
> > >  qph2l   1.0  0.0  0.0    0.0
> > > !Wavevector grid number 2 (series of fine grids, extrapolated from  
> > > interat
> > > forces)
> > >  ng2qpt   20 20 20  ! sample the BZ up to ngqpt2
> > >  ngrids   5         ! number of grids of increasing size
> > >  q2shft   3*0.0
> > > !Thermal information
> > >  nchan   1250   ! # of channels for the DOS with channel width 1  
> > > cm-1
> > >  nwchan  5      ! # of different channel widths from this integer  
> > > down to 1
> > > cm-1
> > >  thmtol  0.030  ! Tolerance on thermodynamical function fluctuations
> > >  ntemper 90     ! Number of temperatures
> > >  temperinc 2.  ! Increment of temperature in K for temperature  
> > > dependency
> > >  tempermin 4.  ! Minimal temperature in Kelvin
> > > # This line added when defaults were changed (v5.3) to keep the  
> > > previous,
> > > old behaviour
> > >  symdynmat 0
> >
> >
> > --
> > Josef W. Zwanziger
> > Professor of Chemistry
> > Canada Research Chair in NMR Studies of Materials
> > Director, Nuclear Magnetic Resonance Research Resource (NMR-3)
> > Dalhousie University
> > Halifax, NS B3H 4J3 Canada
> > tel: +1 (902) 494-1960
> > fax: +1 (902) 494-1867
> > web: http://jwz.chem.dal.ca
> > jzwanzig@gmail.com, jzwanzig@dal.ca