Serious convergence problem (Au and CeO2 mixed system)

[Marcella Iannuzzi]

Dear Yong Li,

your system is not the easiest to treat with DFT. 
I am not too much surprised that you encounter convergence problems. 
The combination of functional, DFT+U, basis-sets and potentials might not 
be optimal.
According to our last experience with CeO2, to get a good description of 
the electronic structure we needed a small core Ce element, with 30 valence 
electrons. 

Have you already tried the following things?
- reduce the mixing coefficient alpha
- increase the smearing temperature
- use a different extrapolation method, e.g., prev_wf
- tighten the eps_default

Kind regards
Marcella


On Saturday, March 26, 2016 at 6:40:18 PM UTC+1, Yong Li wrote:
>
> Dear Sir/Madam,
>
> I was running a large AIMD simulation (about 5200 basis functions) for Au 
> surface supported CeO2 cluster ( (Au(111) surface has180 Au atoms, and Ce
> 10O20 cluster). 
>
> At the beginning, simulation goes well, then it has a very serious 
> convergence problems at around step number of 350. it can't get converged 
> no matter what I do to the SCF control. 
>
> Even if I make it converged coincidentally, but it will not converge after 
> considering Kinetic energy and temperature.
>
> I tried every method I can find， but I can‘t figure it out.
>
> I am depressed and frustrated now, hope someone could help me out with it. 
>  Any suggestions are appreciated!!
>
> The input output file were enclosed in attachment, part of input file is 
> as follows
>
>      
>
>      MULTIPLICITY  1
>      PLUS_U_METHOD  MULLIKEN_CHARGES
>      &SCF
>        MAX_SCF  100
>        EPS_SCF     7.0E-05
>        CHOLESKY  INVERSE
>        SCF_GUESS  ATOMIC
>        ADDED_MOS  400
>        &DIAGONALIZATION  T
>          ALGORITHM  STANDARD
>        &END DIAGONALIZATION
>        &OUTER_SCF  T
>          EPS_SCF     8.0000000000000001E-05
>          MAX_SCF  5
>        &END OUTER_SCF
>        &SMEAR  T
>     #     METHOD  ENERGY_WINDOW
>          METHOD  FERMI_DIRAC
>          ELECTRONIC_TEMPERATURE     3.0000000000000000E+02
>        &END SMEAR
>        &MIXING  T
>          METHOD  BROYDEN_MIXING
>          ALPHA     0.1
>          BETA      1.5
>          NBUFFER  8
>        &END MIXING
>        &PRINT
>          &RESTART  SILENT
>            FILENAME =RESTART.wfn
>            &EACH
>              MD  5
>            &END EACH
>          &END RESTART
>        &END PRINT
>      &END SCF
>      &QS
>        EPS_DEFAULT     1.0000000000000000E-11
>        EPS_PGF_ORB     1.0000000000000001E-05
>        EXTRAPOLATION  ASPC
>        EXTRAPOLATION_ORDER  3
>      &END QS
>      &MGRID
>        CUTOFF     5.0000000000000000E+02
>      &END MGRID
>      &XC
>        DENSITY_CUTOFF     1.0000000000000000E-10
>        GRADIENT_CUTOFF     1.0000000000000000E-10
>        TAU_CUTOFF     1.0000000000000000E-10
>        &XC_GRID
>          XC_SMOOTH_RHO  NN10
>          XC_DERIV  SPLINE2_SMOOTH
>        &END XC_GRID
>        &XC_FUNCTIONAL  NO_SHORTCUT
>          &PBE  T
>          &END PBE
>        &END XC_FUNCTIONAL
>      &END XC
>      &PRINT
>        &MULLIKEN  SILENT
>          FILENAME =md.mulliken
>          &EACH
>            MD  5
>          &END EACH
>        &END MULLIKEN
>      &END PRINT
>    &END DFT
>    &SUBSYS
>
>
>
>
>
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