Dear Wang: All these parameters in the blow article may influence the relaxed structure. *?Designing meaningful density functional theory calculations in materials science?a prime.?* * * *** * On Mon, Sep 20, 2010 at 6:02 PM, Wang Di <didi5158 at gmail.com> wrote:
> Dear Mohnish: > I have used the 'vc-relax' process optimized the cell parameter, however, > the result were seem to deviate from the initial value (experimental value) > too much.The aim of the structure optimizes is for calculating the Raman > spectra of the structure, I think the bad structure ( not coincide to the > experiment) is hard to got the true spectra. So I don't how to deal with the > case. According to your experience, what should I do for the next step? > > Thank you, dear Mohnish, for your kind help. > > > > 2010/9/20 mohnish pandey <mohnish.iitk at gmail.com> > > Dear Wang, >> The 'relax' process optimizes the structure within >> given geometric constraint. It does'nt care for stress. It minimizes force >> only in the given constraint. If you want to minimize the stress also you >> have to do 'vc-relax' calculation, It will give you what you want. >> >> On Mon, Sep 20, 2010 at 11:37 AM, Wang Di <didi5158 at gmail.com> wrote: >> >>> Dear all >>> >>> I perform the relax calculate to the crystal structure. After 11 step >>> bfgs, the total force and total scf correction had reach to the criterion, >>> however, the total stress was so big P=-3443.87. I have no idea about deal >>> with the case, could anyone give some advices? Thanks in advance. >>> >>> the input file >>> : &CONTROL >>> calculation = 'scf' , >>> restart_mode = 'from_scratch' , >>> wf_collect = .true. , >>> outdir = '/lustre/AIOFM/gxgu/workLCAF/5/temp/' , >>> wfcdir = '/lustre/AIOFM/gxgu/workLCAF/5/wftemp/' , >>> pseudo_dir = '/home/AIOFM/gxgu/work/NCPP/' , >>> prefix = 'LCAF' , >>> etot_conv_thr = 1.0D-7 , >>> forc_conv_thr = 1.0D-6 , >>> nstep = 100 , >>> tstress = .true. , >>> tprnfor = .true. , >>> dipfield = .true. , >>> / >>> &SYSTEM >>> ibrav = 4, >>> celldm(1) = 9.42432151, >>> celldm(3) = 1.94804220, >>> nat = 18, >>> ntyp = 4, >>> ecutwfc = 30 , >>> ecutrho = 120 , >>> nosym = .false. , >>> / >>> &ELECTRONS >>> electron_maxstep = 100, >>> conv_thr = 1.0D-10 , >>> / >>> ATOMIC_SPECIES >>> Li 6.94100 03-Li.LDA.fhi.UPF >>> Al 26.98154 13-Al.LDA.fhi.UPF >>> Ca 40.07800 20-Ca.LDA.fhi.UPF >>> F 18.99840 09-F.LDA.fhi.UPF >>> ATOMIC_POSITIONS crystal >>> Li 0.333333333 0.666666667 0.250000000 >>> Li -0.333333333 -0.666666667 -0.250000000 >>> F 0.389997 0.045970 0.148326 >>> F -0.045970 0.344027 0.148326 >>> F -0.344027 -0.389997 0.148326 >>> F -0.045970 -0.389997 0.351674 >>> F -0.344027 0.045970 0.351674 >>> F 0.389997 0.344027 0.351674 >>> F -0.389997 -0.045970 -0.148326 >>> F 0.045970 -0.344027 -0.148326 >>> F 0.344027 0.389997 -0.148326 >>> F 0.045970 0.389997 0.648326 >>> F 0.344027 -0.045970 0.648326 >>> F -0.389997 -0.344027 0.648326 >>> Al 0.666666667 0.333333333 0.250000000 >>> Al -0.666666667 -0.333333333 -0.250000000 >>> Ca 0.000000000 0.000000000 0.000000000 >>> Ca 0.000000000 0.000000000 0.500000000 >>> K_POINTS automatic >>> 16 16 16 0 0 0 >>> >>> best regart >>> >>> Wang Di >>> >>> -- >>> ----------------------------------------------------------------- >>> *Wang Di** >>> The Crystal Lab,* >>> *AnHui Institute of Optics and Fine Mechanics, *** >>> *Chinese Academy of Sciences,** >>> No350. , Shushanhu Road, Hefei, 230031, China**, >>> E-mail: didi5158 @gmail.ocm** ,* >>> ----------------------------------------------------------------- >>> >>> _______________________________________________ >>> Pw_forum mailing list >>> Pw_forum at pwscf.org >>> http://www.democritos.it/mailman/listinfo/pw_forum >>> >>> >> >> >> -- >> Regards, >> MOHNISH, >> ----------------------------------------------------------------- >> Mohnish Pandey >> Y6927262,5th Year dual degree student, >> Department of Chemical Engineering, >> IIT KANPUR, UP, INDIA >> +919235721300 >> ----------------------------------------------------------------- >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> >> > > > -- > ----------------------------------------------------------------- > *Wang Di** > The Crystal Lab,* > *AnHui Institute of Optics and Fine Mechanics, *** > *Chinese Academy of Sciences,** > No350. , Shushanhu Road, Hefei, 230031, China**, > E-mail: didi5158 @gmail.ocm** ,* > ----------------------------------------------------------------- > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- ____________________________________ Hui Wang School of physics, Fudan University, Shanghai, China -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100920/8b778c8f/attachment-0001.htm
