Dear Manoj. The pwcond code was written assuming that the unit cell starts at z=0 and goes in positive z direction, the direction of transport. Quite probable that when you invert the cell it does not work properly... Alexander
? ???, 21/04/2009 ? 23:44 -0400, Manoj Srivastava ?????: > Dear PWSCF users, > I have a question regarding real band structure calculated from > PWCOND. Complex band code requires kx,ky and E as input and gives kz > as output. I have noticed that the answer for kz depends whether you have > unit cell vectors as (a1,a2,a3) or (a1,a2,-a3). I did a calculation for > Cu(001) with 2 atoms tetragonal unit cell, with the following input file - > > & control > calculation='scf' > pseudo_dir = '/home/manoj/espresso-4.0.1/pseudo', > outdir='./', > prefix='cu', > / > &system > ibrav = 0, > celldm(1)=4.7588286373854648 > nat= 2, > ntyp= 1, > ecutwfc =150.0, > occupations='smearing', > smearing='gaussian', > degauss=0.02, > ecutrho=400 > / > &electrons > conv_thr = 1.0e-8 > mixing_beta=0.7 > / > ATOMIC_SPECIES > Cu 63.55 Cu.pz-d-rrkjus.UPF > ATOMIC_POSITIONS > Cu 0.0 0.0 0.0 > Cu 0.5 0.5 0.707106781 > K_POINTS (automatic) > 8 8 8 1 1 1 > CELL_PARAMETERS > 1.0 0.0 0.0 > 0.0 1.0 0.0 > 0.0 0.0 1.414213562 > > &inputcond > outdir='./' > prefixl='cu' > band_file ='bands.cu' > ikind=0 > energy0=2.d0 > denergy=-0.5 > ewind=104.d0 > epsproj=1.d-6 > / > 1 > 0.0 0.0 1.0 > 24 > > This gives me reasonable answer and it matches up with existing results. > Now when I changed a3 to -a3, so that the unit cell now has become > (a1,a2,-a3), the answer does not match up with the previous one. > Just to give you one concrete example- > at Fermi energy for kx,ky (0,0) for unit cell (a1,a2,a3) we get kz=-0.1571 > while for (a1,a2,-a3) we get kz=0.07323. > I understand that for two different set of unit cell vectors we should not > in general expect k_z to match, but this is a very special example, as it > is just mirror symmetry about xy plane. so shouldn't kz in one set have > value -kz in other? > Thanks for your attention. > > Regards, > Manoj Srivastava > Department of Physics > University of Florida > Gainesville, FL > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum -- Alexander Smogunov Email: smogunov at sissa.it Home page: http://people.sissa.it/~smogunov
