CCL: Not able to optimize structure - bisphosphole

 Sent to CCL by: "Daniel  Morales Salazar"
 [danielmoralessalazar91*|*gmail.com]
 Hello,
 I am trying to optimize a molecule with the chemical formula CH52O18P4S4W2,
 which contains thiophenes-phospholes, phenyl groups, and
 tungsten pentacarbonyl substituents.
 It is a large and especially bulky molecule. I have tried using MM and
 Semi-empirical methods (PM6) unsuccessfully. The only converged trial so
 far was one with the "loose" keyword using PM6, which crashed in the
 following calculation with stricter parameters when I did not use the
 keyword. I have tried the keywords calcfc, qc, cartesian, etc.
 Any advice for these types of cases?
 Semi-empirical jobs crash with the message:
 "Symmetry turned off by external request.
  DSYEV returned Info=           2 IAlg= 2 N=     3 NDim=     3 NE2=
 2.
  Diagonalization in DiagDN failed."
 MM methods crash with the message:
 " Error termination request processed by link 9999."
 I have the feeling that the initial geometries are not so bad even! Thank
 you very much for your help.
 Sincerely,
 Daniel Morales Salazar