Does vc-relax change also celldm(3)? BTW, 0.06 for degauss is a tad too large.
Nicola Sent from a tiny keyboard... On 18 May 2013, at 22:15, Dongsheng Zhang <zhdsheng21 at gmail.com> wrote: > Hi, > > I have used vc-relax to get the optimum lattice constant for Ti HCP crystal. > The result is very close to the experiment data. However, when I tried to > calc the total energy at different lattice constant to get the dependency of > total energy on the lattice constant, I got the different answer to the > optimum lattice constant. Could anyone tell me what's wrong in my > simulations? Thanks. > > Dongsheng > > The input for vc-relax method: > > > &control > prefix='ti', > pseudo_dir = '/home1/01993/zhdsheng/espresso/pseudo/', > outdir='/scratch/01993/zhdsheng/Ti_K6L6.0/', > calculation='vc-relax', > restart_mode='from_scratch' > / > &system > ibrav= 4, celldm(1) =6.0,celldm(3) =1.633, nat= 2, ntyp= 1, > occupations='smearing', smearing='marzari-vanderbilt', degauss=0.06, > ecutwfc =150, > > / > &electrons > / > &ions > / > &cell > cell_dynamics='bfgs' > / > ATOMIC_SPECIES > Ti 47.867 Ti.pbe-mt_fhi.UPF > ATOMIC_POSITIONS > Ti 0.000000000000 0.000000000000 0.000000000000 > Ti 0.666666666666 0.333333333333 0.50000000000 > K_POINTS automatic > 6 6 6 1 1 1 > > The optimum lattice constant from this input file is 5.576 > > The input for manual optimization: > template.in: > > &control > prefix='ti', > pseudo_dir = '/home1/01993/zhdsheng/espresso/pseudo/', > outdir='/scratch/01993/zhdsheng/Ti_try/', > restart_mode='from_scratch' > / > &system > ibrav= 4, celldm(1) =alat,celldm(3) =1.633, nat= 2, ntyp= 1, > occupations='smearing', smearing='marzari-vanderbilt', degauss=0.06, > ecutwfc =150, > > / > &electrons > / > &ions > / > ATOMIC_SPECIES > Ti 47.867 Ti.pbe-mt_fhi.UPF > ATOMIC_POSITIONS > Ti 0.000000000000 0.000000000000 0.000000000000 > Ti 0.666666666666 0.333333333333 0.50000000000 > K_POINTS automatic > 6 6 6 1 1 1 > > alat is the lattice variable. The result from this input file is: > > alat etotal > 5.0760 -13.57602170 > 5.1760 -13.61996733 > 5.2760 -13.65721285 > 5.3760 -13.68841125 > 5.4760 -13.71412487 > 5.5760 -13.73484556 > 5.6760 -13.75101618 > 5.7760 -13.76303624 > 5.8760 -13.77128114 > 5.9760 -13.77609614 > 6.0760 -13.77784664 > 6.1760 -13.77685770 > 6.2760 -13.77353840 > 6.3760 -13.76853094 > 6.4760 -13.76290015 > 6.5760 -13.75652953 > 6.6760 -13.74869787 > 6.7760 -13.74207406 > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20130518/0a2740c4/attachment.html
