strange convergence problem about cp2k qmmm

Geng Sun sungen... at
Tue Sep 1 11:54:10 UTC 2015

Hello, everyone,

      I am using the cp2k qmmm to optimize the structure of Pt6 supported 
on Al2O3 surface. But I encounter a problem about the 
      convergence of the qmmm.

     1)  Firstly, the scf of the QM part converges strangely like this:  
All of the QM SCF converges within two steps, and the second number in the 
Covergence column is always zero.

     Step     Update method      Time    Convergence         Total 
energy    Change
     1 Broy./Dav.  0.40E+00    4.1     2.02291583       -81.2822944519 
     2 Broy./Dav.  0.40E+00    5.8     0.0000E+00       -70.8618426104  

  *** SCF run converged in     2 steps ***

    2) Then, the convergence for the structure is also strange. 

     I want the max force is below 0.05 eV/A, so I use something like this

    MAX_ITER 20
    MAX_FORCE [eV*angstrom^-1] 0.05

     But fininally, the program ends "normally" with this massage (shown 
below). Obviously, In the previous Convergence check, the maxforce  is 
 Than what I want. 

  Convergence check :
  Max. step size             =         0.0000000000
  Conv. limit for step size  =         0.0030000000
  Convergence in step size   =                  YES
  RMS step size              =         0.0000000000
  Conv. limit for RMS step   =         0.0015000000
  Convergence in RMS step    =                  YES
  Max. gradient              =         0.5334857508
  Conv. limit for gradients  =         0.0009723453
  Conv. for gradients        =                   NO
  RMS gradient               =         0.0328663882
  Conv. limit for RMS grad.  =         0.0003000000
  Conv. for gradients        =                   NO


 * Specific L-BFGS convergence criteria
 * satisfied .... run CONVERGED!

    So, what is the source of this error in my calculation. 

    Thank you for any advice !

    The input files and the input structure is in the attachment. 

Geng Sun
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