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<style>.hmmessage P{margin:0px;padding:0px}body.hmmessage{FONT-SIZE: 10pt;FONT-FAMILY:Tahoma}</style>Dear all,<br><br>Thank to all your help, I could run a Q-E calculation on my cluster more correctly. Now I can learn to do some <br>simple calculations.<br><br>My first job is to calculate the Anatase-TiO2 lattice cell parameter using Q-E and compare it with literature.<br>I have tested the BFGS for vc-relax, but the cell parameters changed so much that an error was occured with<br>the information 'non orthogonal operation'. Then I used a symmetry-conserving algorithm as the QE manual<br>said. The input file as following,<br> <br>&CONTROL<br> title = 'Anatase lattice' ,<br> calculation = 'vc-relax' ,<br> restart_mode = 'from_scratch' ,<br> outdir = '/home/vega/espresso-4.0/tmp/' ,<br> wfcdir = '/tmp/' ,<br> pseudo_dir = '/home/vega/espresso-4.0/pseudo/' ,<br> prefix = 'Anatase lattice default' ,<br> disk_io = 'none' ,<br> etot_conv_thr = 0.000000735 ,<br> forc_conv_thr = 0.0011668141375 ,<br> nstep = 1000 ,<br> /<br> &SYSTEM<br> ibrav = 6,<br> celldm(1) = 7.135605333,<br> celldm(3) = 2.5121822033898305084745762711864,<br> nat = 12,<br> ntyp = 2,<br> ecutwfc = 25 ,<br> ecutrho = 200 ,<br> /<br> &ELECTRONS<br> conv_thr = 7.3D-8 ,<br> /<br> &IONS<br> ion_dynamics = 'damp' ,<br> /<br> &CELL<br> cell_dynamics = 'damp-w' ,<br> /<br>ATOMIC_SPECIES<br> Ti 47.86700 Ti.pw91-sp-van_ak.UPF <br> O 15.99940 O.pw91-van_ak.UPF <br>ATOMIC_POSITIONS angstrom <br> Ti 0.000000000 0.000000000 0.000000000 <br> Ti 1.888000000 1.888000000 4.743000000 <br> Ti 0.000000000 1.888000000 2.372000000 <br> Ti 1.888000000 0.000000000 7.115000000 <br> O 0.000000000 0.000000000 1.973000000 <br> O 1.888000000 1.888000000 6.716000000 <br> O 0.000000000 1.888000000 4.345000000 <br> O 1.888000000 0.000000000 9.088000000 <br> O 1.888000000 0.000000000 5.141000000 <br> O 0.000000000 1.888000000 0.398000000 <br> O 1.888000000 1.888000000 2.770000000 <br> O 0.000000000 0.000000000 7.513000000 <br>K_POINTS automatic<br> 7 7 3 1 1 1 <br><br>The calculation can be done nearly 600 fs. The last few lines of results file is shown at the bottom.<br>But the cell parameters for Anatase lattice seems to be not perfectly match the results in literature.<br>In the literature, Journal of Physical Chemistry B, 2006, 110, 7464, the author used a conjugate-gradient <br>or quasi-Newton scheme as implemented in VASP to optimaize the geometries. And the cell parameters<br>are a = b = 3.803 A c = 9.603 A c/a = 2.525. But my Q-E result, a= 3.7546166A b= 3.75461729A c= 9.3911A<br>seems to be much smaller than his. I tried times times again, even, the starting geometry is from the <br>exprimental data for Journal of the American Society, 1987,109, 3639, which was also cited by him, the<br>result was still that small. <br><br>I also have tested it in CASTEP, using BFGS and same precision. The CASTEP results were a = b =3.798668A<br>c = 9.693431A c/a = 2.5518, which seemed to be more close to the literature results. The starting geometry<br>was also from Journal of the American Society, 1987,109, 3639. <br><br>I think maybe some parameter in my Q-E input file was wrong. Could you please point it to me?<br><br>thank you for reading. I am waiting for your responding.<br><br><font size="4"><span style="font-family: Lucida Handwriting,Cursive;">Vega Lew</span></font><br>PH.D Candidate in Chemical Engineering<br>State Key Laboratory of Materials-oriented Chemical Engineering<br>College of Chemistry and Chemical Engineering<br>Nanjing University of Technology, 210009, Nanjing, Jiangsu, China<br><br><a href="http://spaces.live.com/spacesapi.aspx?wx_action=create&wx_url=/friends.aspx&mkt=en-us" target="_blank"></a><br /><hr />Connect to the next generation of MSN Messenger <a href='http://imagine-msn.com/messenger/launch80/default.aspx?locale=en-us&source=wlmailtagline' target='_new'>Get it now! </a></body>
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