Dear Kakha and Wien2K users, It also happened to me. Apparently the convergence was also achieved after 14 scf cycles with the output "ec cc and fc_conv 1 1 1", but the program did not stop and began to recalculate again from cycle 1 and then stop after 12 cycles with the output "ec cc and fc_conv 1 1 1".
Best, C?line. Kakhaber Jandieri <Kakhaber.Jandieri at physik.uni-marburg.de> a ??crit??: > Dear Wien2K users, > > As I wrote in my previous letters, I am trying to minimize the atom > positions in GaP supercell where one of the P atoms is replaced by N-N > interstitial molecule. > I found some strange (in my opinion) behaviour of "mini". > Apparently the convergence was achieved after 18 scf cycles with the > output "ec cc and fc_conv 1 1 1". The distance between relaxed N-N > atoms was 1.57 A. > But the program did not stop and began to recalculate again from cycle 1. > After 16 scf cycles the situation was repeated but now the distance > between relaxed N atoms was reduced down to 1.27 A. > And so on without ending. > In my opinion even 1.27 A is already too small value (this is almost > the interatomic distance in isolated N2 molecule), but it was > decreasing further and further. > So, finally I had the problems with overlapping spheres in spite of very > small RMT(N)=1.1 bohr. > > In output file of our cluster I found the following (below some fragment > of this file is shown): > > .............................................................. > .............................................................. > in cycle 18 ETEST: .0001117900000000 CTEST: -.0009873 > ec cc and fc_conv 1 1 1 > >> stop > Fallback to compatibility mode with "old" save_lapw > broyden files deleted, clm*, dmat*, vorb*, vresp*, eece*, scf and struct > files saved under GaPNN_1 > 20.841u 0.352s 0:21.70 97.6% 0+0k 0+20648io 0pf+0w > 0.844u 0.276s 0:01.54 72.0% 0+0k 1272+16896io 8pf+0w > clmextrapol_lapw has generated a new GaPNN.clmsum > ec cc and fc_conv 0 0 0 > in cycle 2 ETEST: 0 CTEST: 0 > ec cc and fc_conv 0 0 0 > in cycle 3 ETEST: 0 CTEST: 0 > ec cc and fc_conv 0 0 0 > ............................................................. > ............................................................. > > > In my opinion 1.57 A is much reasonable value for relaxed N-N distance > then 1.27 A or even smaller value. > I still wonder why the program begins recalculation after the apparently > successful message: "ec cc and fc_conv 1 1 1"? > > Is there some possibility that the reason is the specific position of > N-N interstitial pair? In my initial structure file P(0,0,0) atom was > replaced by N-N interstitial pair having the positions symmetrically > shifted from (0,0,0) along the z-direction. The constrains (0.0, 0.0, > 1.0) in my case.inM file allow the displacement of N atoms only along > the z-direction. My native thought was that may be (0,0,0) is some > specific position in the supercell. If I know correctly, in usual > minimization tasks with substitution impurity, the atom at (0,0,0) > position should have full constrains in all directions. I tried to > replace other P atom in the middle of initial 2x2x2 supercell, but "x > sgroup" always returns the converted supercell where N-N pair is near > (0,0,0), (0.5,0.5,0.5), (0,0,0.5) and so on positions. > > > I will be extremely thankful for any suggestion. > Kakha > > _______________________________________________ > Wien mailing list > Wien at zeus.theochem.tuwien.ac.at > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >
