[DFTB-Plus-User] FW: Problem in SCC convergence

[Gabriele Penazzi]

Dear Fateme,

when you calculate the bandstructure you don't want to solve again the
SCC problem, you rather want to upload a good input charge obtained from
a previous calculation.

See the DFTB+ recipes, the procedure is well explained there
http://www.dftb-plus.info/fileadmin/DFTB-Plus/public/recipes/html/

Gabriele

On 08/17/2015 12:28 PM, Fateme Hooshmand wrote:
> 
> ________________________________________
> From: Fateme Hooshmand
> Sent: Monday, August 17, 2015 11:55 AM
> To: DFTB-Plus-User at dftb-plus.info
> Subject: Problem in SCC convergence
> 
> Dear DFTB+ Users
> I did DOS calculation without any problem in SCC convergence but the Band-calculation have not got any result due to convergence problem in SCC. In my knowledge in both of this calculations have the same method for projecting wave functions but only with selected strips of k-points for band structure. So, this is the only difference between these two input files.  These are input files for DOS and Band calculations:
> DOS:
> Driver ={
> }
> Hamiltonian = DFTB {
> SCC = Yes
> SCCTOlerance = 1e-7
> MaxSCCIterations = 2000
> MaxAngularMomentum = {
> C = "p";
> }
> SlaterKosterFiles = Type2FileNames {
> C-C = "C-C.skf"
> Prefix = "./SK/"
> Separator = "-"
> Suffix = ".skf"
> }
> Filling = Fermi {
> Temperature [Kelvin] = 1.000000000000000E-008
> }
> KPointsAndWeights = SupercellFolding {
>      1 0  0
>      0 1  0
>      0 0  11
>      1 1  1
>  }
> }
> Analysis {
>   ProjectStates {
>     Region {
>       Atoms = C
>       ShellResolved = Yes
>       Label = "dos_C"
>     }
> #####################################################
> band:
> Driver ={
> }
> Hamiltonian = DFTB {
> SCC = Yes
> SCCTOlerance = 1e-7
> MaxSCCIterations = 1
> MaxAngularMomentum = {
> C = "p";
> }
> SlaterKosterFiles = Type2FileNames {
> C-C = "C-C.skf"
> Prefix = "./SK/"
> Separator = "-"
> Suffix = ".skf"
> }
> Filling = Fermi {
> Temperature [Kelvin] =  1.000000000000000E-008
> }
> ReadInitialCharges = Yes
> KPointsAndWeights = Klines{
>  1  0.0 0.0  0.0
>  1  0.5 0.5 -0.5
>  }
> }
> Options = {
> WriteResultsTag = Yes
> RestartFrequency = 0
> }
> ParserOptions {
> ParserVersion = 4
> IgnoreUnprocessedNodes = Yes
> }
> ################################################
> error message:
> ********************************************************************************
> ** Geometry step: 0
> ********************************************************************************
> 
>   iSCC Total electronic   Diff electronic      SCC error
>     1   -0.13272902E+03    0.00000000E+00    0.19625336E-04
> 
>  Total Energy:                    -121.0746363928 H
>  Total Mermin free energy:        -121.0746363928 H
> ERROR!
> -> SCC is NOT converged, maximal SCC iterations exceeded
> 
> 
> 
> PLEASE let me know how I can fixed this problem ?
> Thank you in advance
> best
> 
> 
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> 

-- 
--
Dr. Gabriele Penazzi
BCCMS - University of Bremen

http://www.bccms.uni-bremen.de/
http://sites.google.com/site/gabrielepenazzi/
phone: +49 (0) 421 218 62337
mobile: +49 (0) 151 19650383