CCL:G: SCF convergence problem with M06L functional in Gaussian 09

 Sent to CCL by: J C Womack [jw5533^-^]
 It is also worth considering the possibility that the meta-GGA exchange
 functional (M06-L) itself is misbehaving.
 It is known that certain meta-GGAs (including M06-L) produce
 singularities for some electron densities, resulting in SCF convergence
 problems. See for example:
 Gräfenstein, J., Izotov, D. & Cremer, D. Avoiding singularity problems
 associated with meta-GGA (generalized gradient approximation) exchange
 and correlation functionals containing the kinetic energy density. The
 Journal of Chemical Physics 127, 214103 (2007).
 On 26/02/16 05:12, Bulumoni Kalita wrote:
 > Sent to CCL by: "Bulumoni  Kalita" [bulumoni-]
 > Dear CCL users,
 >        I have optimized tetrahedral structure of Pd4 cluster in
 (UB3LYP/LANL2DZ) level in Gaussian 09. I wanted to repeat the calculation in
 (UM06L/LANL2DZ) level.  However, SCF is not converging in this case.  Rather it
 is fluctuating between to range of values.  I have tried using SCF(xqc,
 maxcycle=500), opt(maxcycle=500) etc.
 > Please give your valuable suggestions to overcome this problem.>
 James C. Womack