[DFTB-Plus-User] Radicals
Bálint Aradi
aradi at uni-bremen.de
Wed Nov 24 12:46:33 CET 2021
Dear Nicolás
welcome among the DFTB+ users! :-)
The problem is not really DFTB specific, but the rather general DFT
problem of describing biradicals. Biradicals would require many-body
Hamiltonians, which DFT with the KS-ansatz can not describe properly.
In your case, the level of the isolated H is very close to an occupied
level of the molecule. Since there is only one Fermi level in the
system, electrons will be distributed between the two states, despite
the fact, that they are quite far away from each other in space.
Best regards,
Bálint
On 23.11.21 17:21, Nicolás F. Barrera Pavez via DFTB-Plus-User wrote:
> Dear all,
>
> I am a new DFTB + user and I am trying to optimize a structure
> consisting of hydrogenated coronene (doublet) and a neutral hydrogen
> atom (doublet) on the surface. The whole system is singlet. The problem
> is that the calculation starts with the hydrogen atom charged as -1, it
> is not what I want. I tried to give the initial charges, but the
> calculation is not modified. What am I doing wrong ?
> Please suggest how to resolve this.
>
> Thanks,
> Nicolás
>
> Geometry = GenFormat {
> 38 C
> H C
> # Index Type Coordinates
> 1 2 0.010956 -0.864985 -0.691563
> 2 2 0.035477 -0.864985 -5.040157
> 3 2 0.035413 -0.864985 -3.621145
> 4 1 0.000064 0.000187 0.000765
> 5 2 -1.168272 -0.865005 -7.183019
> 6 2 -1.198468 -0.865005 -5.764334
> 7 2 1.275126 -0.864965 -5.760252
> 8 2 1.274068 -0.864965 -7.183847
> 9 2 0.026345 -0.864986 -7.874284
> 10 2 2.512325 -0.864945 -5.047669
> 11 2 2.514010 -0.864944 -3.617491
> 12 2 1.277018 -0.864965 -2.897258
> 13 2 3.752559 -0.864924 -2.911471
> 14 2 4.976596 -0.864904 -3.657533
> 15 2 4.971309 -0.864904 -5.028879
> 16 2 3.744422 -0.864925 -5.763355
> 17 2 3.715271 -0.864925 -7.186957
> 18 2 2.522258 -0.864945 -7.874302
> 19 1 2.519942 -0.864945 -8.963406
> 20 1 4.658447 -0.864910 -7.731714
> 21 1 -2.111341 -0.865021 -7.728171
> 22 1 0.026904 -0.864986 -8.963226
> 23 1 5.919993 -0.864889 -3.113245
> 24 1 5.911137 -0.864889 -5.579491
> 25 2 -2.429960 -0.865025 -5.030599
> 26 2 -2.443429 -0.865025 -3.663786
> 27 2 -1.217848 -0.865005 -2.898105
> 28 1 -3.367216 -0.865041 -5.586028
> 29 1 -3.389827 -0.865041 -3.124560
> 30 2 -1.228147 -0.865005 -1.515694
> 31 2 1.294488 -0.864964 -1.480643
> 32 1 -2.181784 -0.865021 -0.987686
> 33 2 3.732592 -0.864924 -1.496917
> 34 1 4.673725 -0.864909 -0.949551
> 35 2 2.527352 -0.864944 -0.805352
> 36 1 2.533850 -0.864944 0.283967
> 37 1 0.000092 -1.730158 0.000764
> 38 1 0.000064 5.000187 0.000765
> }
> Driver = ConjugateGradient {
> MovedAtoms = 1:-1 # Move all atoms in the system
> MaxForceComponent = 1.0e-5 # Stop if maximal force below 1.0e-4
> MaxSteps = 200 # Stop after maximal 100 steps
> OutputPrefix = "geom.out" # Final geometry in geom.out.{xyz,gen}
> }
> Hamiltonian = DFTB {
> SCC = yes
> Charge = 0.0000000000000000
> MaxSCCIterations = 1000
> MaxAngularMomentum { # Maximal l-value of the various species
> C = "p"
> H = "s"
> }
> SlaterKosterFiles = {
> C-C = "/home/max/Downloads/3OB/C-C.skf"
> C-H = "/home/max/Downloads/3OB/C-H.skf"
> H-C = "/home/max/Downloads/3OB/H-C.skf"
> H-H = "/home/max/Downloads/3OB/H-H.skf"
> }
> SpinPolarisation = colinear {
> UnpairedElectrons = 0
> RelaxTotalSpin = Yes
> InitialSpins = {}
> }
> SpinConstants = {
> H = {
> -0.072
> }
> C = {
> -0.023
> }
> ShellResolvedSpin = No
> }
> InitialCharges = {
> AllAtomCharges = {
> -0.06769461
> 0.00579206
> -0.00339778
> 0.07078826
> -0.09381019
> 0.03353591
> 0.00409556
> 0.04194961
> -0.10226583
> 0.00460835
> 0.00358489
> 0.00963840
> 0.03985005
> -0.09801495
> -0.09422754
> 0.03675780
> -0.09585258
> -0.09905321
> 0.07352457
> 0.07309346
> 0.07257816
> 0.07380965
> 0.07352378
> 0.07332021
> -0.09065398
> -0.10187854
> 0.05239546
> 0.07295901
> 0.07375513
> -0.14800507
> 0.01676019
> 0.07633470
> -0.09873572
> 0.07402982
> -0.10391580
> 0.07003247
> 0.07078829
> 0.00000001
> }
> }
> PolynomialRepulsive = {}
> ShellResolvedSCC = No
> OldSKInterpolation = No
> RangeSeparated = None {}
> SCCTolerance = 1.0000000000000001E-005
> HCorrection = None {}
> ElectricField = {}
> OnSiteCorrection = {}
> Dispersion = {}
> Solvation = {}
> ThirdOrder = No
> ThirdOrderFull = No
> Differentiation = FiniteDiff {
> Delta = 1.2207031250000000E-004
> }
> ForceEvaluation = "Traditional"
> Mixer = Broyden {
> MixingParameter = 0.20000000000000001
> InverseJacobiWeight = 1.0000000000000000E-002
> MinimalWeight = 1.0000000000000000
> MaximalWeight = 100000.00000000000
> WeightFactor = 1.0000000000000000E-002
> }
> Filling = Fermi {
> Temperature = 0.0000000000000000
> }
> }
> Analysis = {
> MullikenAnalysis = Yes
> CalculateForces = Yes
> }
> Options = {
> WritedetailedOut = Yes
> WriteResultsTag = Yes
> WriteChargesAsText = Yes
> }
> ParserOptions {
> ParserVersion = 9
> }
>
> /Saludos,/
> /Nicolás F. Barrera Pavez
> Estudiante de Licenciatura en Ciencias con mención en Química/
> /Facultad de Ciencias/
> /Universidad de Chile/
>
>
> _______________________________________________
> DFTB-Plus-User mailing list
> DFTB-Plus-User at mailman.zfn.uni-bremen.de
> https://mailman.zfn.uni-bremen.de/cgi-bin/mailman/listinfo/dftb-plus-user
>
--
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.bccms.uni-bremen.de/cms/people/b-aradi/
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