[Pw_forum] Could we plot HOMO & LUMO for slab model in QE
Dear Vega, With pp.x you can plot |psi|^2 for any band at a given k-point. Check out the Doc/INPUT_PP.txt for more info. Hope that helps, Nick On Sun, 24 Jan 2010, vega lew wrote: > Dear all, > > I want to explain something in very chemical viewpoint. So HOMO and LUMO > is very important. I am wondering whether we could plot HOMO, HOMO-1, > HOMO-2 or LUMO etc for slab model in QE. > > thank you for reading > > best, > > vega > > -- > > > == > Vega Lew ( weijia liu) > Graduate students > State Key Laboratory of Materials-oriented Chemical Engineering > Nanjing University of Technology, 210009, Nanjing, Jiangsu, China > > *** > Email: vegalew at gmail.com > Office: Room A705, Technical Innovation Building, Xinmofan Road 5#, > Nanjing, Jiangsu, China > > *** > > > * Nicholas E. Singh-Miller Prof. Marzari Group (quasiamore.mit.edu) Materials Science and Engineering Massachusetts Institute of Technology 13-4066 (617)324-0372 *
[Pw_forum] What happens at REALLY large ectuwfc?
Hi Brad, probably the calculation is not converged. Try a few things: 1) is the total energy at 2000Ry lower than at 200 Ry ? At self-consistency, it should be, even infinitesimally, due to the variaitonal principle. 2) try different recipes: cg vs davidson, and different initalizations (atomic+random, random, etccc). nicola Brad Malone wrote: > I happened to stumble upon something today that I thought was > unusual. The problem is illustrated in a simple example: if you take > the following basic cubic Si input file and, say, the Si.pz-vbc.UPF > pseudopotential from the QE website and do a test for convergence with > respect to ectutwfc. > > If we look at the 4 bands that are calculated we see the following > results: > > At ecutwfc=40 Ry: -5.1740 7.0370 7.0370 7.0370 > ecutwfc=100Ry: -5.1746 7.0369 7.0369 7.0369 > ecutwfc=200Ry:-5.1746 7.0369 7.0369 7.0369 > Now try >ecutwfc=2000Ry: -5.2862 6.9066 6.9066 10.2399 > > Now why do the values change? If I look at the output file for the > 2000 Ry case I see that there is a negative starting charge: > > Initial potential from superposition of free atoms > Check: negative starting charge= -0.057614 > > But still, why is this? The usual answer for a negative starting > charge is to increase the wavefunction cutoff, although I suspect > that's not the problem in this case. > > So besides the using of a 2000 Ry cutoff for silicon, what else is > wrong here? > > Best, > Brad > UC Berkeley > > > &control >prefix = 'si' >calculation = 'scf' >restart_mode = 'from_scratch' >wf_collect = .false. >tstress = .true. >tprnfor = .true. >outdir = './' >wfcdir = './' >pseudo_dir = './' > / > &system >ibrav = 0 >celldm(1) = 10.2612 >nat = 2 >ntyp = 1 >nbnd = 4 >ecutwfc = 2000.0 > / > &electrons >electron_maxstep = 100 >conv_thr = 1.0d-10 >mixing_beta = 0.7 >diago_full_acc = .true. > / > CELL_PARAMETERS cubic > 0.0 0.5 0.5 > 0.5 0.0 0.5 > 0.5 0.5 0.0 > ATOMIC_SPECIES > Si 28.086 Si.pz-vbc.UPF > ATOMIC_POSITIONS crystal > Si -0.12500 -0.12500 -0.12500 > Si 0.12500 0.12500 0.12500 > K_POINTS automatic > 1 1 1 0 0 0 > > > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -- - Prof Nicola Marzari Department of Materials Science and Engineering 13-5066 MIT 77 Massachusetts Avenue Cambridge MA 02139-4307 USA tel 617.4522758 fax 2586534 marzari at mit.edu http://quasiamore.mit.edu
