Dear all,
I am trying, as a training exercise, to recover the adsorption energy of
a boron atom on a Cu(111) slab, which according to the literature should
be around -2 eV. The energy is given by: E(ads) = E(slab+B) - E(slab) -
E(B). For E(B), if I use a B atom in the slab’s box, the energy is very
negative and unrealistic (around -4 eV). If I use the energy of a B atom
from the 3D boron crystal, the energy becomes positive (around +2 eV),
so there is no adsorption. Below you will find my input file for the
slab+B system. I use the same parameters for the other two energies. The
BSSE correction (a few tenths of an eV) does not change the observed
trend. Am I making a mistake somewhere and/or do you have any
suggestions to help me recover the correct value?
Thank you in advance for you help.
Regards,
Roland.
_______________________________________
SystemName CuB test
SystemLabel cu_b
NumberOfAtoms 46
NumberOfSpecies 2
XC.functional GGA
XC.authors PBE
MaxSCFIterations 200
%block ChemicalSpeciesLabel
1 29 Cu # Species index, atomic number, species label
2 5 B # Species index, atomic number, species label
%endblock ChemicalSpeciesLabel
PAO.FixSplitTable T
PAO.EnergyShift 20 meV
PAO.SplitNorm 0.15
MeshCutoff 300.000000 Ry
ElectronicTemperature 50.000000 K
#
MD.TypeOfRun CG # Broyden also possible
MD.NumCGsteps 200
#
SolutionMethod diagon
SCF.DM.Converge true # Converge SCF step wrt density
matrix (default: 1e-4)
SCF.H.Converge true
DM.NumberPulay 3
DM.History.Depth 3
#SCF Mixer -> Density pour les systèmes difficiles
SCF.Mix Hamiltonian
# Mixer 0.5 reduit le nombre de pas pour des systèmes faciles
# Mixer 0.001 augmente le nombre de pas pour des systèmes difficiles
SCF.Mixer.Weight 0.05
SCF.Mixer.History 6
SCF.Mixer.Method Pulay
MaxSCFIterations 100
SCF.DM.Tolerance 5.0E-5 eV
SCF.H.Tolerance 0.0005 eV
MD.MaxStressTol 0.0025 eV/Ang**3
# Nouvelle ligne pour la force entre atomes
MD.MaxForceTol 0.01 eV/Ang
# Use old data to save time
MD.UseSaveXV
MD.UseSaveDM
# Save atomic coordinates at each step
WriteCoorStep .true.
WriteMDHistory .true.
PAO.BasisType split
PAO.BasisSize DZP
LatticeConstant 1.0000 Ang
%block LatticeVectors
7.65797 0.00000 0.00000
3.82898 6.63199 0.00000
0.00000 0.00000 24.00000
%endblock LatticeVectors
AtomicCoordinatesFormat Ang
%block AtomicCoordinatesAndAtomicSpecies
3.829 0.7369 1.80 2 # Atome de B en site cfc
0.0 0.0 0.0 1
1.2763 2.2107 0.0 1
2.5527 4.4213 0.0 1
2.5527 0.0 0.0 1
3.829 2.2107 0.0 1
5.1053 4.4213 0.0 1
5.1053 0.0 0.0 1
6.3816 2.2107 0.0 1
7.658 4.4213 0.0 1
0.0 1.4738 -2.0842 1
1.2763 3.6844 -2.0842 1
2.5527 5.8951 -2.0842 1
2.5527 1.4738 -2.0842 1
3.829 3.6844 -2.0842 1
5.1053 5.8951 -2.0842 1
5.1053 1.4738 -2.0842 1
6.3816 3.6844 -2.0842 1
7.658 5.8951 -2.0842 1
1.2763 0.7369 -4.1685 1
2.5527 2.9476 -4.1685 1
3.829 5.1582 -4.1685 1
3.829 0.7369 -4.1685 1
5.1053 2.9476 -4.1685 1
6.3816 5.1582 -4.1685 1
6.3816 0.7369 -4.1685 1
7.658 2.9476 -4.1685 1
8.9343 5.1582 -4.1685 1
0.0 0.0 -6.2527 1
1.2763 2.2107 -6.2527 1
2.5527 4.4213 -6.2527 1
2.5527 0.0 -6.2527 1
3.829 2.2107 -6.2527 1
5.1053 4.4213 -6.2527 1
5.1053 0.0 -6.2527 1
6.3816 2.2107 -6.2527 1
7.658 4.4213 -6.2527 1
0.0 1.4738 -8.3369 1
1.2763 3.6844 -8.3369 1
2.5527 5.8951 -8.3369 1
2.5527 1.4738 -8.3369 1
3.829 3.6844 -8.3369 1
5.1053 5.8951 -8.3369 1
5.1053 1.4738 -8.3369 1
6.3816 3.6844 -8.3369 1
7.658 5.8951 -8.3369 1
%endblock AtomicCoordinatesAndAtomicSpecies
%block kgrid_Monkhorst_Pack
12 0 0 0.
0 12 0 0.
0 0 1 0.
%endblock kgrid_Monkhorst_Pack
SaveTotalPotential T
SaveTotalCharge T
SaveElectrostaticPotential T
