<DIV> Dear pwscf users</DIV>
<DIV> I run vc-relax to optimize the lattice constant of ZnO unit cell,my input file and out file as follows:</DIV>
<DIV> </DIV>
<DIV> &CONTROL<BR> title = ZnOVC ,<BR> calculation = 'vc-relax' ,<BR> restart_mode = 'from_scratch' ,<BR> pseudo_dir = '/root/espresso-3.2.3/pseudo/' ,<BR> prefix = ZnO ,<BR> etot_conv_thr = 1.D-5 ,<BR> nstep = 100 ,<BR> tstress = .true. ,<BR> tprnfor = .true. ,<BR> dt = 100 ,<BR> tefield = .false. ,<BR> /<BR> &SYSTEM<BR> ibrav = 4,<BR> celldm(1) = 6.14161,<BR> celldm(3) = 1.6022,<BR> nat = 4,<BR> ntyp = 2,<BR> ecutwfc = 40 ,<BR> ecutrho = 300 ,<BR> nosym = .true. ,<BR> nbnd = 25,<BR> occupations = 'smearing' ,<BR> degauss = 0.002 ,<BR> smearing = 'methfessel-paxton' ,<BR> lda_plus_u = .false. ,<BR> /<BR> &ELECTRONS<BR> conv_thr = 1.D-8 ,<BR> startingpot = 'atomic' ,<BR> startingwfc = 'atomic' ,<BR> mixing_mode = 'plain' ,<BR> mixing_beta = 0.6 ,<BR> diagonalization = 'david' ,<BR> diago_full_acc = .true. ,<BR> /<BR> &IONS<BR> ion_dynamics = 'damp' ,<BR> /<BR> &CELL<BR> cell_dynamics = 'damp-w' ,<BR> /<BR>ATOMIC_SPECIES<BR> Zn 65.00000 Zn.pz-van_ak.UPF <BR> O 16.00000 O.pz-rrkjus.UPF <BR>ATOMIC_POSITIONS crystal <BR> Zn 0.333333333 0.666666667 0.000000000 1 1 1 <BR> O 0.333333333 0.666666667 0.381700000 1 1 1 <BR> Zn 0.666666667 0.333333333 0.500000000 1 1 1 <BR> O 0.666666667 0.333333300 0.881700000 1 1 1 <BR>K_POINTS automatic <BR> 4 4 4 0 0 0 </DIV>
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<DIV> Program PWSCF v.3.2.2 starts ...<BR> Today is 18Aug2008 at 23: 7:36 </DIV>
<DIV> Ultrasoft (Vanderbilt) Pseudopotentials</DIV>
<DIV> Current dimensions of program pwscf are:</DIV>
<DIV> ntypx = 10 npk = 40000 lmax = 3<BR> nchix = 6 ndmx = 2000 nbrx = 14 nqfx = 8</DIV>
<DIV> Title: <BR> ZnOVC </DIV>
<DIV><BR> bravais-lattice index = 4<BR> lattice parameter (a_0) = 6.1416 a.u.<BR> unit-cell volume = 321.4357 (a.u.)^3<BR> number of atoms/cell = 4<BR> number of atomic types = 2<BR> kinetic-energy cutoff = 40.0000 Ry<BR> charge density cutoff = 300.0000 Ry<BR> convergence threshold = 1.0E-08<BR> beta = 0.6000<BR> number of iterations used = 8 plain mixing<BR> Exchange-correlation = SLA PW PBE PBE (1434)<BR> nstep = 100</DIV>
<DIV> celldm(1)= 6.141610 celldm(2)= 0.000000 celldm(3)= 1.602200<BR> celldm(4)= 0.000000 celldm(5)= 0.000000 celldm(6)= 0.000000</DIV>
<DIV> crystal axes: (cart. coord. in units of a_0)<BR> a(1) = ( 1.000000 0.000000 0.000000 ) <BR> a(2) = ( -0.500000 0.866025 0.000000 ) <BR> a(3) = ( 0.000000 0.000000 1.602200 ) </DIV>
<DIV> reciprocal axes: (cart. coord. in units 2 pi/a_0)<BR> b(1) = ( 1.000000 0.577350 0.000000 ) <BR> b(2) = ( 0.000000 1.154701 0.000000 ) <BR> b(3) = ( 0.000000 0.000000 0.624142 ) </DIV>
<DIV><BR>.......</DIV>
<DIV>.......</DIV>
<DIV>outfile:</DIV>
<DIV><BR> Final estimate of lattice vectors (input alat units)<BR> 1.011331020 0.000000000 0.000000000<BR> -0.505665507 0.875838356 0.000000001<BR> 0.000000000 -0.000000002 1.627761723<BR> final unit-cell volume = 334.0064 (a.u.)^3<BR> input alat = 6.1416 (a.u.)</DIV>
<DIV>CELL_PARAMETERS (alat)<BR> 1.011331020 0.000000000 0.000000000<BR> -0.505665507 0.875838356 0.000000001<BR> 0.000000000 -0.000000002 1.627761723</DIV>
<DIV>ATOMIC_POSITIONS (crystal)<BR>Zn 0.333333347 0.666666677 0.000438189<BR>O 0.333333356 0.666666677 0.380132292<BR>Zn 0.666666690 0.333333345 0.500438960<BR>O 0.666666695 0.333333331 0.880132483</DIV>
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<DIV>from the outfile I can see the c/a=1.627761723 and from the final unit-cell volume =334.0064 (a.u.)^3,I can compute the a=6.189678(Bohr)=3.2754(A)¡£From the value of caculating ,we can see that the c/a and a are both bigger than the experiment , I don't konw whether the result is right or wrong .</DIV>
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<DIV>Anybody who know about the question and give me the useful advice will be appreciated .</DIV>
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<DIV>Sincerely </DIV>
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