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[XIFAN WU <wuxifan@physics.rutgers.edu>]

Hi,

I have read your input file, till now I have some questions about you
response function input file.

1. You set the rfdir2 1 0 0, so it means that you only want the response
in the first direction, if you set it as 1 1 1 then three directions of
phonons will be calculated.

2. The parameter rfatpol is not explictly set, so the default value means
only the response function calculations of the first atom defined in your
xred will be computed.

These two seem to have nothing to do with your rigid-atom elastic
constants output, these maybe the reason why you got warnigs in anaddb.
but I do have a question when you compared the rigid-ion
elastic constants with the experimental one. Usually experimental elastic
constant means the relaxed-ion elastic constant, so when we use the
anaddb, we do need all the phonons are calculated at gamma point because
relaxed-ion elastic constant coupled the gamma phonons when you relax the
atoms which is the usual experimental enviroment. For more details about
how they are working in ABINIT, you could read the following paper inside
the abinit package:
abinit_4.3.3/Infos/Theory/lr.pdf

good luck,

xifan wu

On Wed, 22 Dec 2004, Jorissen Kevin wrote:

> Dear abinit users,
>
> This is a follow up to a thread about the same calculation that appeared on 
> the forum a few weeks ago.
> I will ask three questions in this e-mail :
> 1/ about the values I obtained from abinis 4.3.3
> 2/ about problems using anaddb 4.3.3
> 3/ about problems using abinis 4.4.2 and 4.4.3
>
>
> 1/ *************************************************************
> I try to calculate elastic constants of NiTi using abinit v. 4.3.3, 
> compiled with ifc 7.1 on a intel xeon machine running linux debian.
>
> Thanks to the help of the forum, I was able to complete the 'abinis' part 
> of the calculation, using the following input file NiTi.in :
>
> >> BEGINNING OF FILE
> #TiNi calculation of elastic constants
> ndtset 2
> # For reduction of memory demands
> mkmem 0
> mkqmem 0
> mk1mem 0
> mffmem 0
> # Set 1 : initial self-consistency
> kptopt1 1
> tolvrs1 1.0d-19
> iscf1 5
> # Set 2 : response-function strain calculation
> rfdir2 1 0 0
> nqpt2 1
> qpt2 0 0 0
> rfstrs2 3
> getwfk2 -1
> kptopt2 2
> tolvrs2 1.0d-12
> iscf2 3
> diemix2 0.5
> prtwf2 0
> #common input data
> acell 3*5.7165
> ecut 76
> natom 2
> nband 18
> ngkpt 12 12 12
> nshiftk 1
> shiftk 0.5 0.5 0.5
> nstep 200
> ntypat 2
> rprim 1 0 0 0 1 0 0 0 1
> occopt 4
> tsmear 0.02
> typat 1 2
> xred 0.0 0.0 0.0 0.5 0.5 0.5
> zatnum 22 28
> << END OF FILE
>
> The log file shows me no reason to mistrust the calculation.
> I show here a small section of the NiTi.out file :
> >>BEGINNING OF SECTION
>
>   Rigid-atom elastic tensor , in cartesian coordinates,
>      j1       j2             matrix element
>   dir pert dir pert     real part    imaginary part
>    1    5   1    5    0.0073636566    0.0000000000
>    1    5   1    6    0.0000000000    0.0000000000
>    2    5   1    5    0.0058674162    0.0000000000
>    2    5   1    6    0.0000000000    0.0000000000
>    3    5   1    5    0.0058674162    0.0000000000
>    3    5   1    6    0.0000000000    0.0000000000
>    1    6   1    5    0.0000000000    0.0000000000
>    1    6   1    6    0.0024582518    0.0000000000
>    2    6   1    5    0.0000000000    0.0000000000
>    2    6   1    6    0.0000000000    0.0000000000
>    3    6   1    5    0.0000000000    0.0000000000
>    3    6   1    6    0.0000000000    0.0000000000
>
> << END OF SECTION
>
> That means elastic constants of 108 GPa, 86 GPa and 36 GPa are found, while 
> in experiment values of  about 160, 130 and 35 are measured.  FP(L)APW 
> results typically get like 180, 150 and 50 - by no means perfect, but a lot 
> better than the numbers I found with abinit.
> When repeating the calculation using ecut 95 and ngkpt 16 16 16, changes in 
> the calculated values are smaller than 1 GPa.
> (I also repeated the calculation using executables compiled with -O0 for 
> all libraries and subroutines, with no difference w.r.t. the optimized 
> executables.)
>
> 2/ 
> **********************************************************************************
> I tried to use anaddb (although I was told in a previous mail on the forum 
> that for this simple material, this is not necessary), using an input file 
> taken from the tests :
>
> << BEGINNING OF FILE
> !ithis is the continuing calculation of t01 in abaddb
> !for GaAs in hypothetical wurzite (hexagonal) structure
> !the flags
> dieflag 3  !the frequency dependent dielectric tensor is calculated
> elaflag  3  !the flag for the elastic constant
>  piezoflag 3
> instrflag 1  !the flag for the internal strain tensor
> !the effective charge part
> asr 1
> chneut  1
> ! Wavevector list number 1
> nph1l 1 !number of phonons in list 1
> qph1l  0.0 0.0 0.0 1.0 !the Gamma point
> ! Wave vector list no. 2
> nph2l 1  !number of phonons in list 2
> qph2l 0.0 0.0 1.0 0.0  ! why here
> >> END OF FILE
>
> I get suspicious comments and a bug warning in the corresponding log file 
> ab.log :
> << SECTION FROM AB.OUT
>  gtblk9 : COMMENT -
>   The blok     1 does not match the requirement
>   because it lacks the element with
>   idir1,ipert1,idir2,ipert2,index=    3    1    3    1   51
>  gtblk9 :
>   Unable to find block corresponding to the following specifications :
>  Type (rfmeth) =  1
>  ider qphon(3)         qphnrm   rfphon rfelfd rfstrs
>    1  0.00  0.00  0.00  0.00      1      2      0
>    2  0.00  0.00  0.00  0.00      1      2      0
>  asria9 : imposition of the ASR for the interatomic forces.
>  fxphas : BUG -
>   The eigenvector number   3 has zero norm.
>   Action : contact ABINIT group.
>  Delivered    1 WARNINGs and   9 COMMENTs to log file.
>  leave_new : decision taken to exit ...
> FORTRAN STOP  1
> >> END SECTION FROM AB.OUT
>
> Full ab.out and ab.log files from anaddb are attached to this mail.
> Commenting some statements in the ab.in file that I considered unnecessary 
> did not change the behaviour of anaddb at all.
>
>
> 3/ 
> ***********************************************************************************
> I tried also to use the 4.4 series of abinit, since it seems a lot of 
> progress has been made for rf calculations.
> However, both 4.4.2 and 4.4.3 crash with an adress error in the second 
> dataset :
>
> >> PART OF LOG FILE
>  inwffil: copy wf on disk file NiTi_1WF1
>  loper3 about to open unit  12 for file=NiTi_1WF2
>   chkexi : openexit,iexit,tsec(1)-tcpu_last           1           0
>    22.1201782226562
>      iter   2DEtotal(Ha)       deltaE(Ha) residm    vres2
>  getcut: wavevector=  0.0000  0.0000  0.0000  ngfft=  48  48  48
>          ecut(hartree)=     76.000   => boxcut(ratio)=   2.13963
>  Non-SCF iterations; k pt #    1  k=  0.04167  0.04167  0.04167  band 
> residuals:
>
> ** Address Error **
>
> End of diagnostics
> << END PART OF LOG FILE-
>
> If the rest of these output files are interesting, I will put them on the 
> forum / ftp server.
>
>
>
>
> Thank you for your time,
>
> Kevin.
>
>
>
>
> Kevin Jorissen
>
> EMAT - Electron Microscopy for Materials Science   
> (http://webhost.ua.ac.be/emat/)
> Dept. of Physics
>
> UA - Universiteit Antwerpen
> Groenenborgerlaan 171
> B-2020 Antwerpen
> Belgium
>
> tel  +32 3 2653249
> fax + 32 3 2653257
> e-mail kevin.jorissen@ua.ac.be
>
>