Dear Forum,<br><br><br>Could anyone give me some hints about how to adjust "qcutz,q2sigma,ecfixed" in vc-cp?<br><br>I have some difficulties. After wave function initialization, the input file are for zero pressure zero temperature are following.<br>
(After zero pressure zero temperature, I will elevate temperature with verlet algorithm.) <br> But when I use different ecfixed with fixed qcutz and q2sigma, the volumes at equilibrium are different.<br>some is close to that without "qcutz,q2sigma,ecfixed" used. some are 100 ( toal around 3000) different from that without "qcutz,q2sigma,ecfixed" used.<br>
(In my case, I am sure the fnosep, wmass, and emass is good enough.)<br><br>I attached the voluem evolution figure. In the figure, from step 200-1200 is belong to the following input file. <br>before 200 step is wave initialization, after 1200 step, I increased temperature.<br>
<br> <br>Thank you very much!<br><br>WANG Riping<br>2011.3.7<br><br><br><br>&control<br> calculation = 'vc-cp' ,<br> prefix = 'SiO2-mog' ,<br> restart_mode = 'restart' ,<br> nstep = 1000 , <br>
iprint = 1 , <br> isave = 10 ,<br> dt = 5.0 ,<br> ndr = 51 , <br> ndw = 52 ,<br> tstress = .TRUE. ,<br> tprnfor = .TRUE. ,<br> saverho = .TRUE. , <br> disk_io = 'high' ,<br> /ekin_conv_thr = 1.0d-3 ,<br>
/etot_conv_thr = 5.0d-3 ,<br> /forc_conv_thr = 1.0d-2 , <br> pseudo_dir ='~/espresso/pseudo' ,<br> outdir = './' ,<br> /<br> &system<br> ibrav = 14 , <br> celldm(1) = 16.021289268 , <br>
celldm(2) = 0.558448710 , <br> celldm(3) = 1.245135500 , <br> celldm(4) = -0.000028830 , <br> celldm(5) = -0.007432130 , <br> celldm(6) = 0.000064680 ,<br> nat = 36 , <br> ntyp = 2 , <br> ecutwfc = 30 , <br>
ecutrho = 240.0 ,<br> nr1b = 16 , <br> nr2b = 16 , <br> nr3b = 16 ,<br> qcutz = 150.0 , <br> q2sigma = 2 , <br> ecfixed = 16.8 ,<br> /<br> &electrons<br> electron_dynamics = 'sd' , <br>
emass = 400 , <br> emass_cutoff = 3. , <br>/<br>&ions <br> ion_dynamics = 'sd' ,<br>/<br>&cell <br> cell_dynamics = 'pr' ,<br> press = 0 ,<br> wmass = 300 , <br> /<br>ATOMIC_SPECIES<br>
O 16.00 O.pbe-van_ak.UPF<br> Si 28.00 Si.pbe-n-van.UPF<br>ATOMIC_POSITIONS (crystal)<br> ...<br><br><br><br><br><br clear="all"><br>-- <br><div>******************************************************************************<br>
WANG Riping<br>Ph.D student, </div>
<div>Institute for Study of the Earth's Interior,Okayama University,<br>827 Yamada, Misasa, Tottori-ken 682-0193, Japan<br>Tel: +81-858-43-3739(Office), 1215(Inst)</div>
<div>E-mail: <a href="mailto:wang.riping.81@gmail.com" target="_blank">wang.riping.81@gmail.com</a><br>******************************************************************************<br><br><br></div><br>