[ase-users] Vibrational calculation for Cu-Cl on Cu fails

[s042547 at student.dtu.dk]

Dear Ase users,

 I would like to perform a vibrational calculation for Cu-Cl adsorbed on a
Cu(2x2x3) slab. The calculator I am using is dacapo, and the script is as
follows:

..
calc = Jacapo(nc=name_system+'.nc',
              kpts=(4,4,1),
              pw = 26*Ry,
              dw = 35*Ry,
              nbands = nelecbands,
              atoms = slab,
              xc = 'RPBE',
              dipole = True)

vib = Vibrations(slab, indices = [12,13])
vib.run()
vib.summary(T=523)
..

 As you see only Cu and Cl are displaced. When I run the script, it
generates 12 pckl files (as expected, all have the same size, so nothing
seems to be wrong there) and then I get the error:
..
File "/home/dobr/APPS/ase-3.4.1.1765/ase/vibrations.py", line 210, in read
    omega2, modes = np.linalg.eigh(self.im[:, None] * H * self.im)
  File
"/home/dobr/APPS/Numpy-1.3.0//lib64/python2.4/site-packages/numpy/linalg/linalg.py",
line 924, in eigh
    raise LinAlgError, 'Eigenvalues did not converge'
numpy.linalg.linalg.LinAlgError: Eigenvalues did not converge
..

 If I only displace the chlorine atom, then everything works fine, and I
get 3 frequencies.

 Do you have any ideas why numpy fails when calculating the
eigenfrequencies and how to correct this problem?

(I attach the full script and the error message)

Best regards
Dominik Bjørn Rasmussen
M.Sc. Student, DTU
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