Jiayu and Matteo, PRB volume 12 was published in 1975.
The paper discussing the contribution of dU/dV is actually: Phys. Rev. B 79, 125124 (2009). Regards, Han On Sun, April 4, 2010 10:36 pm, Matteo Cococcioni wrote: > > Dear Jiayu > > in order to fully account the effects of the +U correction on pressure > one should include a contribution from dU/dV too. > you may find this reference useful: > > Phys. Rev. B 12, 125124 (2009) > > regards, > > Matteo > > > Jiayu Dai wrote: >> Dear Matteo, >> >> Thanks for your comments. I am using the BOMD (pwscf). In my case, at >> high density, i would expect the U should be different with the change >> of ionic structures. In particular, i am concerning about the pressure. >> I found a strange thing: the pressure with LDA+U is lower than the >> pressure without U adding. As my experience, th pressure should be >> larger when we added the U parameter, is it right? >> >> Besides, all the cases using LDA+U is about the transition metals, which >> has the d or f electrons. How about the s or p electrons? >> >> Thanks. >> >> Jiayu >> >> >> >> >> Dear Jiayu, >> >> are you talking about Car-Parrinello MD or Born-Oppenheimer MD (run with >> pwscf)? >> In any case lda+U MD is implemented in the sense that the code computes >> the forces and the stress >> as derivatives of the lda+U energy functional. However it is not able >> to account for the variation >> of U with atomic position or with the cell. So it is a dynamics at fixed >> U. >> To account for this variation one would need to evaluate dU/dR or >> dU/d\epsilon (R and \epsilon being atomic >> positions and strains). Some work in this direction has been recently >> done (not sure it's >> published yet) by Kulik and Marzari. >> If the structure you are interested in doesn't change dramatically >> during the MD run I would expect >> that keeping the same U is not too bad. but this is just my guess. >> >> regards, >> >> Matteo >> >> >> Jiayu Dai wrote: >> >>> Dear developers, >>> >>> I have some doubts about the molecular dynamics calculations using >>> LDA+U. First, is LDA+U performed in MD calculations? Because i did not >>> find the Hubbard energy in the output file of MD. Second, i think the >>> value of U be dependent on the temperature and density, also on the >>> ionic structures. Therefore, since ionic positions are different in >>> each time step, is U different at each time step? If so, the >>> performance of LDA+U should be very difficult in MD. >>> >>> I did not know if what i said is right. Hope experts comment on this >>> problem. >>> >>> Thanks a lot. >>> >>> Jiayu >>> ------------------------------------------- >>> Jiayu Dai >>> Department of Physics >>> National University of Defense Technology, >>> Changsha, 410073, P R China >>> ----------------------------------------- >>> _______________________________________________ >>> Pw_forum mailing list >>> Pw_forum at pwscf.org >>> http://www.democritos.it/mailman/listinfo/pw_forum >>> >>> >> >> >> >> _______________________________________________ >> 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 > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum >
