Thank you! I'm now reading up on the wurtzite unit cell to make sure I get my input file correct, Helen
----- Original Message ----- From: "Marcel Mohr" <[email protected]> To: "PWSCF Forum" <pw_forum at pwscf.org> Sent: Tuesday, January 15, 2008 1:07 PM Subject: Re: [Pw_forum] wurtzite AlN > Hi, > > wurtzite has 4 atoms in the unit cell. > > Cheers Marcel > > > On Tue, 15 Jan 2008, Helen wrote: > >> Hi, >> I've successfully calculated the bandstructure for zinc-blende AlN, and I >> wanted to do the same for wurtzite AlN but am running into problems. I >> started off with a=5.88 a.u. c/a=1.600 and u=0.382 , I then kept a and c >> constant and altered u. The results showed that u needed to be smaller >> but when I reached u=0.369 my scf calculations stopped converging. I >> tried using both cg and davidson diagonalization. I then tried keeping u >> constant and altering c, I don't get convergence problems but I get >> unrealistically small values of c. Also the bandgap data I'm getting is >> nonsense (no band gap at all). Perhaps I have a mistake in my input file? >> Thank you for your help and advice, >> Dr. Helen Eisenberg (Fritz Haber Center, Hebrew University) >> >> &control >> calculation='scf' >> restart_mode='from_scratch', >> tstress = .true. >> tprnfor = .true. >> prefix='alas', >> pseudo_dir = '$PSEUDO_DIR/', >> outdir='$TMP_DIR/' >> / >> &system >> ibrav= 4, celldm(1) =5.88, celldm(3)=1.600, nat= 2, ntyp= 2, >> ecutwfc =80.0, nbnd = 8, >> nr1=32, >> nr2=32, >> nr3=32, >> ecutrho = 240.0 >> / >> &electrons >> conv_thr = 1.0d-6 >> mixing_beta = 0.7 >> / >> ATOMIC_SPECIES >> Al 26.98 Al.vbc.UPF >> N 14.007 N.pz-vbc.UPF >> ATOMIC_POSITIONS >> Al 0.00 0.00 0.00 >> N 0.00 0.00 0.611 >> K_POINTS (automatic) >> 4 4 4 0 0 0 >> EOF > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum >
