the new tutorial on the calculation of U can be downloaded from this webpage:
http://www.quantum-espresso.org/wiki/index.php/QESB09#First_week Matteo Cococcioni wrote: > Dear Ali, > > on the wiki page of quantum-espresso you should be able to find a new > tutorial on the calculation of U. Please download it > and run the scripts in there following the instructions. > > > > ali kazempour wrote: > >> Dear all >> >> From Linear response calculation ,I get for TiO2 bulk U=5.73, But when >> I double the unit cell in z direction and again compute U ,I get three >> different value for Ti atoms.(U=5.63,5.46,5.70). >> >> > > what are these three values? I assume they are what you get with > supercells of three different sizes. is this correct? if it is the only > strange thing is that the intermediate value is lower than the other > two. otherwise you got pretty nice convergence of U which is what you > want to achieve. Is there any particular reason (apart computational > cost) why you only enlarge the cell in z direction? > > >> Why these values are not same . what is the main reason? Does it in >> numerical variation errors? >> ANother question: >> When we perturb D level by alpha, it give rise to change in d >> occupancy . Is it correct that if we impose negative alpha , the >> occupation becomes less than initial state .? >> >> > > no. positive alpha -- > decrease in total n. but you need to look at the > right n.... > > >> for Ti isolated atom for apha=0.1 tr[ns(na)] after first-iteration >> equal to the 0.002 and at the end of calculation is 2.327 while we >> know that for Ti, tr[ns(na)] =2.000. Does it seems to be correct.? >> >> Number of iteration with fixed ns = 0 >> Starting ns and Hubbard U : >> enter write_ns >> U( 1) = 0.0000 >> alpha( 1) = 0.1000 >> atom 1 Tr[ns(na)]= 2.0000000 >> atom 1 spin 1 >> eigenvalues: 0.4000000 0.4000000 0.4000000 0.4000000 0.4000000 >> eigenvectors >> 1 1.0000000 0.0000000 0.0000000 0.0000000 0.0000000 >> 2 0.0000000 1.0000000 0.0000000 0.0000000 0.0000000 >> 3 0.0000000 0.0000000 1.0000000 0.0000000 0.0000000 >> 4 0.0000000 0.0000000 0.0000000 1.0000000 0.0000000 >> 5 0.0000000 0.0000000 0.0000000 0.0000000 1.0000000 >> occupations >> 0.400 0.000 0.000 0.000 0.000 >> 0.000 0.400 0.000 0.000 0.000 >> 0.000 0.000 0.400 0.000 0.000 >> 0.000 0.000 0.000 0.400 0.000 >> 0.000 0.000 0.000 0.000 0.400 >> atom 1 spin 2 >> eigenvalues: 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 >> eigenvectors >> 1 1.0000000 0.0000000 0.0000000 0.0000000 0.0000000 >> 2 0.0000000 1.0000000 0.0000000 0.0000000 0.0000000 >> 3 0.0000000 0.0000000 1.0000000 0.0000000 0.0000000 >> 4 0.0000000 0.0000000 0.0000000 1.0000000 0.0000000 >> 5 0.0000000 0.0000000 0.0000000 0.0000000 1.0000000 >> occupations >> 0.000 0.000 0.000 0.000 0.000 >> 0.000 0.000 0.000 0.000 0.000 >> 0.000 0.000 0.000 0.000 0.000 >> 0.000 0.000 0.000 0.000 0.000 >> 0.000 0.000 0.000 0.000 0.000 >> nsum = 2.0000000 >> exit write_ns >> >> > > this is not the first iteration. this is what the initial guess of the > on-site occupations the code does to start the calculation > > > >> Atomic wfc used for LDA+U Projector are NOT orthogonalized >> Starting wfc are 9 atomic + 1 random wfc >> >> total cpu time spent up to now is 13.34 secs >> >> per-process dynamical memory: 326.3 Mb >> >> Self-consistent Calculation >> >> iteration # 1 ecut= 45.00 Ry beta=0.70 >> CG style diagonalization >> c_bands: 3 eigenvalues not converged >> c_bands: 2 eigenvalues not converged >> ethr = 1.00E-12, avg # of iterations = 40.4 >> enter write_ns >> U( 1) = 0.0000 >> alpha( 1) = 0.1000 >> atom 1 Tr[ns(na)]= 0.0021401 >> atom 1 spin 1 >> eigenvalues: 0.0000001 0.0000001 0.0000001 0.0009883 0.0009883 >> eigenvectors >> 1 0.0000000 -0.8803392 -0.4743427 0.0000000 0.0013927 >> 2 0.0000000 -0.4743432 0.8803400 0.0000000 -0.0000040 >> 3 0.0000000 0.0012242 0.0006642 0.0000000 0.9999990 >> 4 -0.8886820 0.0000000 0.0000000 -0.4585240 0.0000000 >> 5 0.4585240 0.0000000 0.0000000 -0.8886820 0.0000000 >> occupations >> 0.001 0.000 0.000 0.000 0.000 >> 0.000 0.000 0.000 0.000 0.000 >> 0.000 0.000 0.000 0.000 0.000 >> 0.000 0.000 0.000 0.001 0.000 >> 0.000 0.000 0.000 0.000 0.000 >> >> > > this is the first iteration! the problem is, in my opinion, that you > didn't start this calculation from wfc and potential saved from the scf > unperturbed run, but from scratch (that's why the code has to make the > initial guess for the n). > > regards, > > Matteo > >> ---------------------------------- and end of the file is >> : >> End of self-consistent calculation >> enter write_ns >> U( 1) = 0.0000 >> alpha( 1) = 0.1000 >> atom 1 Tr[ns(na)]= 2.3270531 >> atom 1 spin 1 >> eigenvalues: 0.1574294 0.1574294 0.1574294 0.9273825 0.9273825 >> eigenvectors >> 1 0.0000000 -0.4359030 -0.7986559 0.0000000 0.4148945 >> 2 0.0000000 0.7269732 -0.0406891 0.0000000 0.6854592 >> 3 0.0000000 -0.5305643 0.6004109 0.0000000 0.5983379 >> 4 -0.9258933 0.0000000 0.0000000 -0.3777851 0.0000000 >> 5 0.3777851 0.0000000 0.0000000 -0.9258933 0.0000000 >> occupations >> 0.927 0.000 0.000 0.000 0.000 >> 0.000 0.157 0.000 0.000 0.000 >> 0.000 0.000 0.157 0.000 0.000 >> 0.000 0.000 0.000 0.927 0.000 >> 0.000 0.000 0.000 0.000 0.157 >> >> >> Ali Kazempour >> Physics department, Isfahan University of Technology >> 84156 Isfahan, Iran. Tel-1: +98 311 391 3733 >> Fax: +98 311 391 2376 Tel-2: +98 311 391 2375 >> >> >> ------------------------------------------------------------------------ >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> >> > > > -- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Matteo Cococcioni Department of Chemical Engineering and Materials Science, University of Minnesota 421 Washington Av. SE Minneapolis, MN 55455 Tel. +1 612 624 9056 Fax +1 612 626 7246 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
