Dear Sagar. You can describe the fcc structure with tetragonal unit cell: a1=(a/2,-a/2,0) a2=(a/2,a/2,0) a3=(0,0,a) having two atoms at 0 and at 0.5*(a1+a2+a3). Of course, you can use fcc as the leads but as it is implemented in pwcond now your unit cell should be monoclinic (tetragonal is a particular case of monoclinic), i.e. such that a3 is perpendicular to both a1 and a2 and the direction of transport is a3. The one-dimensional complex bands are calculated at fixed (k1,k2) along the k3 direction which will coincide with a3. In the setup above with k1=k2=0 they will be complex bands in [001] direction. Anyway, [100] (what you want to calculate) and [001] (what is presented in the example 12) are equivalent directions in fcc.
Best regards, Alexander On Thursday 24 April 2008 08:21, ambavale sagar wrote: > Dear Smogunov sir, > Sorry but i can'at understand that why only tetragonal must be used as > electrode bulk geometry? can't we use FCC? > and how to define this(fcc) geometry using tetragonal unit cell with only > two atoms? > > sagar > > %%%%%%%%%%%%%%%%%%%%%%%%%% > Dear Sagar. > This is because you should use the tetragonal > unit cell with two atoms per cell like in the example 12. > Regards, > Alexander > > On Tuesday 22 April 2008 11:24, ambavale sagar wrote: > > sorry, i forgot to attach scf file and my signature. so resending the > > entire mail. i am using espresso 4.0cvs2 for calculating complex band > > structure of al bulk in 100 direction( for 001 it is given in example > > 12). this gives me following errror: > > > > from in init_cond : error # 1626817 > > wrong nrztot > > > > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% > >%% %%% > > > > stopping ... > > > > the input file for complex band is : > > > > &inputcond > > outdir='/db/sagar/tmp/' > > prefixl='al_bulk' > > band_file ='bands.albulk' > > ikind=0 > > energy0=10.d0 > > denergy=-0.4d0 > > ewind=1.d0 > > epsproj=1.d-3 > > delgep = 1.d-12 > > cutplot = 3.d0 > > / > > 1 > > 0.0 0.0 1.0 > > 60 > > > > while the file for scf calculation is: > > > > &control > > calculation='scf' > > restart_mode='from_scratch', > > pseudo_dir = '/db/espresso4.0cvs2/pseudo/', > > outdir='/db/sagar/tmp/', > > prefix='al_bulk' > > tprnfor = .true. > > tstress = .true. > > / > > &system > > ibrav= 2, celldm(1) =7.50, nat= 1, ntyp= 1, ecutwfc =15.0, > > occupations='smearing', smearing='marzari-vanderbilt', degauss=0.05 > > / > > &electrons > > diagonalization='david' > > mixing_beta = 0.7 > > / > > ATOMIC_SPECIES > > Al 26.98 Al.vbc.UPF > > ATOMIC_POSITIONS > > Al 0.00 0.00 0.00 > > K_POINTS (automatic) > > 2 2 2 1 1 1 > > > > > > Sagar Ambavale > > PhD student > > The M.S.University of Baroda > > Inida > > Best Jokes, Best Friends, Best Food and more. Go to > http://in.promos.yahoo.com/groups/bestofyahoo/
