Dear Mojtaba, I wil try to answer your questions one by one.
On Fri, Jan 27, 2012 at 2:50 PM, Mojtaba Rahimi <mrahimi93 at gmail.com> wrote: > Dear all > > I'm using QE to calculate U-hubbard for graphene. I've used 18 atom super > cell which has hexagonal structure, and linear response approach code, which > is written by Dr. cococcioni. I've modified cococcioni's shell scripts which > has been located at training part of QE website for graphene, but I've > confronted to some problem and I have some question about this cod as well. > I hope someone could answer me. > > Thanks in advance > > I prefer to propose my question at first: > > As you know in graphene pz orbital which is perpendicular to graphene plane, > and play the most important role in transport and optical properties, isn't > localized, but that cod is written for localized orbital such as d, and f(at > least from my knowledge). can I use this cod for graphene? in principle yes. I'm not sure why you want to compute the U for graphene. have you tried to see if U has any effect on the actual calculation? > > At atomic position file, the three first line specifies the parameter cell. > Is it important that parameter cell to be cubic or it doesn't matter what it > is? > in principle it is not necessary the cell to be cubic. it should work with any cell. > In this approach we can just determine the on-site hubbard potential. f I > tended to determine the nearest neighbor and next nearest neighbor hubbard > potential, how would I do them by this code? > if you mean intersite interactions those come for free from the off-diagonal elements of the interaction matrix (of which U is the diagonal). > And my problems are: > > when I calculated the U for super cell dimension n=1-2, I obtained a > negative U, which i think is wrong because U have to be positive. > yes it should not be the case. but I am not able to tell you what the problem is. > When I changed the super cell dimension to n=3,... I encountered to a > problem which I mentioned below. How can I over com to this problem. I would > be grateful if somebody could help me. > seems like a problem of memory. probably you should increase the size of some arrays. this is my guess. hope this helps. Matteo > *** glibc detected *** ./r.x: free(): invalid next size (normal): 0x09d29018 > *** > > ======= Backtrace: ========= > > [0x82507db] > > [0x825368b] > > [0x81f4324] > > [0x81f4299] > > [0x805181d] > > [0x804824a] > > [0x823805d] > > [0x8048131] > > ======= Memory map: ======== > > 08048000-082c3000 r-xp 00000000 08:11 77561870 > /home/nano2/mojtaba-work/plan/isolated-graphen/U-graphene/Ucalc/r.x > > 082c3000-082ce000 rwxp 0027b000 08:11 77561870 > /home/nano2/mojtaba-work/plan/isolated-graphen/U-graphene/Ucalc/r.x > > 082ce000-088de000 rwxp 082ce000 00:00 0 > > 09d23000-09d45000 rwxp 09d23000 00:00 0 > > 55555000-556d2000 rwxp 55555000 00:00 0 > > 55700000-55721000 rwxp 55700000 00:00 0 > > 55721000-55800000 ---p 55721000 00:00 0 > > ffc05000-ffc2a000 rwxp 7ffffffd9000 00:00 0 [stack] > > ffffe000-fffff000 r-xp ffffe000 00:00 0 > > forrtl: error (76): IOT trap signal > > > > -- > ----- > Mojtaba Rahimi (Mr.) > Master of science -condensed matter, > > Email: mrahimi93 at gmail.com > > Phone:+ 98-9134515197 > > > > _______________________________________________ > 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
