Dear Giuseppe and all others, first of all, sorry for the duplicated message in the list. I have not received any message to my initially registered e-mail address and was already thinking that my question has not got into the pw_forum.
> Dear Yuri > There are technical and physical reasons behind your unrealistic results. > technical: > >> N 14.00700 N.pbe-van_ak.UPF >> H 1.00800 H.pbe-van_ak.UPF >> C 12.01100 C.pbe-van_ak.UPF >> Cu 63.54600 Cu.pbe-n-van_ak.UPF > >> ecutwfc = 25 , > >In the case of ultrasoft pseudopotential ecutrho has to be indicated, >having a value between >6*ecutwfc and 10*ecutwfc (convergence should be reached with respect >to all such values, but I >perform satisfactorily converged CuPc calculations with the same >pseudos by using >ecutwfc=35/ecutrho=280 cutoffs...) Ok, I will use no less then 35 and 280 for ecutwfc and ecutrho. >> tot_charge = 0.000000, >> starting_magnetization(1) = 0.0, >> starting_magnetization(2) = 0.0, >> starting_magnetization(3) = 0.0, >> exxdiv_treatment = 'gygi-baldereschi' , > >useless keywords (in this case...). Starting_magnetization(4) = x with >0.0 < x < 1.0 is enough to >break the spin symmetry. > >> nat = 33, > >The copper phthalocyanine (CuPc) has 57 atoms. Have you checked the >structure? I calculate a _polymer_ of CuPc. The unit cell I've created contains 33 atoms, that should be correct. >> ibrav = 6, >> celldm(1) = 20.11677, >> celldm(3) = 2.59367, > >your molecules embedded into a tetragonal cell seems to be placed at a >z distance of about 30 A from >its periodically repeated image... Check the exact use of the >celldm(i) variables... Thank you! I was not careful in reading the manual and thought that these parameters are just lengths of vectors. >Physical: > >Molecular crystals stay together because of dispersion interactions. >As you are not using any kind >of dispersion correction, you will never obtain meaningful results on >lattice parameters. There is >plenty of theoretical papers investigating the CuPc molecule. I >suggest to start with them... Ok, thanks for pointing on that. Now I can play with calculations further. Sincerely, Yura
