[DFTB-Plus-User] DFTB+ for cobalt with spins

[Vladimir Lipp]

Dear all,

I am trying to run DFTB+ 24.1 for a spin-polarized cobalt. It usually 
works fine, but some specific configurations and electronic temperatures 
it breaks with the following error:


======================================

ERROR!
-> Fermi level search did not converge.
Note: The following floating-point exceptions are signalling: 
IEEE_UNDERFLOW_FLAG IEEE_DENORMAL
ERROR STOP

Error termination. Backtrace:
#0  0x4e4a8e in __dftbp_common_globalenv_MOD_abortprogram
     at /mnt/scratch/aradi/BUILD/gnu/src/dftbp/common/globalenv.f90:136
#1  0xa410a6 in __dftbp_dftb_etemp_MOD_efilling
     at /mnt/scratch/aradi/BUILD/gnu/src/dftbp/dftb/etemp.f90:180
#2  0x57fa19 in getfillingsandbandenergies
     at /mnt/scratch/aradi/BUILD/gnu/src/dftbp/dftbplus/main.f90:3542
#3  0x58d034 in getdensityfromdensediag
     at /mnt/scratch/aradi/BUILD/gnu/src/dftbp/dftbplus/main.f90:2800
#4  0x5931ef in getdensity
     at /mnt/scratch/aradi/BUILD/gnu/src/dftbp/dftbplus/main.f90:2588
#5  0x5b0976 in __dftbp_dftbplus_main_MOD_processgeometry
     at /mnt/scratch/aradi/BUILD/gnu/src/dftbp/dftbplus/main.f90:1266
#6  0x5b3dbd in __dftbp_dftbplus_main_MOD_rundftbplus
     at /mnt/scratch/aradi/BUILD/gnu/src/dftbp/dftbplus/main.f90:218
#7  0x4e3a6a in dftbplus
     at /mnt/scratch/aradi/BUILD/gnu/app/dftb+/dftbplus.f90:32
#8  0x4af68c in main
     at /mnt/scratch/aradi/BUILD/gnu/app/dftb+/dftbplus.f90:10

======================================



If I change the input electronic temperature from 3.142012939453E+03 to 
3000, it converges with no errors. Can anybody give a hint concerning 
how I can overcome this problem? My dftb_in.hsd file is the following:


Geometry = GenFormat {
<<< "CoordinatesDFTB+.dat"
}
Driver = {
}
Hamiltonian = DFTB {
SCC = Yes
SCCTolerance = 1e-3
MaxSCCIterations = 1000
OrbitalResolvedSCC = Yes
SlaterKosterFiles {
Co-Co = "Co-Co.skf"
}
  MaxAngularMomentum {
  Co = "d"
}
Filling = MethfesselPaxton {
Temperature [K] =     3.142012939453E+03
}
KPointsAndWeights = SuperCellFolding {
5 0 0
0 5 0
0 0 5
0.0 0.0 0.0
}
Charge =     2.682000715060E-02
SpinPolarisation = Colinear {
UnpairedElectrons =    1.6636081141018849E+01
RelaxTotalSpin = Yes
InitialSpins = {
AtomSpin = {
Atoms = 1:-1
SpinPerAtom = 1.0
}
}
}
SpinConstants = {
Co = {
# 4s   4p   4d
-0.01644085  -0.01644085  -0.00339546   # 4s
-0.01644085  -0.01644085  -0.00339546   # 4p
-0.00339546  -0.00339546  -0.01617359   # 3d
}
}
Mixer = Broyden {
MixingParameter = 0.15
}
}
Options {
   WriteResultsTag = Yes
}
{}Analysis = {
#OrbitalResolved = Yes
CalculateForces = Yes
ProjectStates {
Region {
Atoms = Co
ShellResolved = Yes
Label = "pdos.Co"
}
}
}
ParserOptions {
ParserVersion = 6
}




Thank you in advance!

Best regards,
Vladimir