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<pre><br><br>One of the origins of this bad convergence is the selection of ecurho. For ultra-soft pseudo-potentials,the ecurho should be 10X of ecutwfc<br>and I had not considered it well. <br><br> <br>very best wishes<br>Masoud Nahali<br>SUT<br> <br><br><br>Dear Quantum Espresso users<br> <br>I have done a 'vc-relax' calculation to find the cell parameters of graphite. The selected k-points are (4*4*4) and automatic.<br> <br>obtained cell parameters:<br> a = 2.469,<br> b = 2.469,<br> c = 7.069,<br> <br>then I used these values to 'relax' the atoms in cell (k-points were 4*4*4 too) . Finally I used the obtained cell parameters to find the proper k-points for graphite.<br>I performed some 'scf' calculations with different k-points and in whole of them the cell parameters and positions were what is obtained from the relax part with 4*4*4 k-points.<br> <br>'scf' energy with different k-points:<br> <br>k-points energy <br> <br>(4*4*4): -45.5732791969 Ry <br> <br>(5*5*5): -45.57637408 Ry<br> <br>(6*6*6): -45.57592043 Ry<br> <br>(7*7*7): -45.57420434 Ry<br> <br>(8*8*8): -45.57474553 Ry<br> <br>(9*9*9): -45.57500776 Ry<br> <br>(10*10*10): -45.57454272 Ry<br> <br>(11*11*11): -45.57464463 Ry<br> <br>(12*12*12): -45.57480118 Ry<br> <br>(13*13*13): -45.57462800 Ry<br> <br>(14*14*14): -45.57463705 Ry<br> <br>(15*15*15): -45.57473135 Ry<br> <br>(16*16*16): -45.57465384 Ry<br>I appreciate if one help me to find the answers to these questions:<br>1. Is the whole procedure plausible ?2. why a energy convergence is not occurred after selecting these high values of k-points?3. How can I find the proper k-points safely?<br>the input file for 'scf' calculation:<br>&CONTROL<br> calculation = "scf",<br> pseudo_dir = "/home/koa/soft/qe4.2/espresso-4.2/pseudo",<br> outdir = "/home/koa/tmp",<br> etot_conv_thr= 1.0D-4,<br> forc_conv_thr= 1.0D-3,<br> nstep=150,<br> /<br>&SYSTEM<br> ibrav = 4,<br> a = 2.469,<br> b = 2.469,<br> c = 7.069,<br> cosab = -0.5,<br> cosac = 1.0,<br> cosbc = 1.0,<br> nat = 4,<br> ntyp = 1,<br> ecutwfc = 30.D0,<br> ecutrho = 200.D0<br> occupations = 'smearing'<br> smearing ='mp', <br> degauss = 0.01,<br> nspin = 2,<br> starting_magnetization(1)= 1.0,<br> /<br>&ELECTRONS<br> conv_thr = 1.D-6,<br> mixing_beta = 0.7D0,<br> diagonalization = "david",<br>/<br>&IONS<br> ion_dynamics="bfgs"<br>/<br>ATOMIC_SPECIES<br>C 12.0107 C.pbe-van_ak.UPF<br>ATOMIC_POSITIONS {angstrom}<br>C 0.000000000 0.000000000 0.000000000<br>C 0.000000000 1.425534302 0.000000000<br>C 0.000000000 0.000000000 3.534553118<br>C 1.234548920 0.712767151 3.534553118<br> <br>K_POINTS {automatic}<br>16 16 16 1 1 1<br> <br>the vc-relax input: <br>&CONTROL<br> calculation = "vc-relax",<br> pseudo_dir = "/home/koa/soft/qe4.2/espresso-4.2/pseudo",<br> outdir = "/home/koa/tmp",<br> etot_conv_thr= 1.0D-4,<br> forc_conv_thr= 1.0D-3,<br> dt=70,<br> nstep=150,<br> /<br>&SYSTEM<br> ibrav = 4,<br> a = 2.456,<br> b = 2.456,<br> c = 6.696,<br> cosab = -0.5,<br> cosac = 1.0,<br> cosbc = 1.0,<br> nat = 4,<br> ntyp = 1,<br> ecutwfc = 30.D0,<br> ecutrho = 200.D0<br> occupations = 'smearing'<br> smearing ='mp', <br> degauss = 0.01,<br> nspin = 2,<br> starting_magnetization(1)= 1.0,<br> /<br>&ELECTRONS<br> conv_thr = 1.D-6,<br> mixing_beta = 0.7D0,<br> diagonalization = "david",<br>/<br>&IONS<br> ion_dynamics="bfgs"<br>/<br>&CELL<br>cell_dynamics = 'damp-w',<br>press = 0.0 ,<br>/<br>ATOMIC_SPECIES<br>C 12.0107 C.pbe-van_ak.UPF<br>ATOMIC_POSITIONS {angstrom}<br> C 0.00000000 0.00000000 0.00000000<br> <br> C 0.00000000 1.41797226 0.00000000<br> <br> C 0.00000000 0.00000000 3.34800000<br> <br> C 1.22800000 0.70898613 3.34800000<br> <br>K_POINTS {automatic}<br>4 4 4 1 1 1<br> <br>very best wishes<br> <br><br> </pre> <br /><hr />Hotmail: Free, trusted and rich email service. <a href='https://signup.live.com/signup.aspx?id=60969' target='_new'>Get it now.</a></body>
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