question on the optimization of twisted graphene 3.84 |
- Date: 2023/05/09 16:08
- Name: Tao Zhang
<zhangtao_scu@outlook.com>
- Hi, there,
when I use the OpenMX to optimize the structure of twisted graphene(bilayer,3.84and 1084 atoms), the calculation can be finished normally. Howerver, OpenMX seems can not produce a reasonable interlayer distance of twisted graphene. the interlayer distance is around 4.0A calculated by OpenMX, meanwhile the interlayer distance is around 3.6A and the experiment result of that is around 3.4A. So, it seems OpenMX produced large error on this points. For better solve the problem, I list some key setting of my setting file here.
Species.Number 1
<Definition.of.Atomic.Species
C C6.0-s2p2d1 C_PBE19
Definition.of.Atomic.Species>
Atoms.Number 1084
Atoms.SpeciesAndCoordinates.Unit FRAC
<Atoms.SpeciesAndCoordinates
....
Atoms.SpeciesAndCoordinates>
Atoms.UnitVectors.Unit Ang
<Atoms.UnitVectors
40.641229025494596 0.000000000000000 0.000000000000000
20.306345482666647 35.204499967541288 0.000000000000000
0.000000000000000 0.000000000000000 22.003256209490957
Atoms.UnitVectors>
###################0 relax and 1 fixed#########################
<MD.Fixed.Cell.Vectors
0 1 1
0 0 1
1 1 1
MD.Fixed.Cell.Vectors>
scf.XcType GGA-PBE
scf.SpinPolarization off
scf.ElectronicTemperature 300.0
scf.energycutoff 300.0
scf.maxIter 200
scf.EigenvalueSolver band
scf.Kgrid 1 1 1
scf.Mixing.Type rmm-diisk
scf.Init.Mixing.Weight 0.05
scf.Min.Mixing.Weight 0.01
scf.Max.Mixing.Weight 0.30
scf.Mixing.History 25
scf.Mixing.StartPulay 15
scf.criterion 1.0e-7
#############geometric optimization##############
scf.ExtCharge.History 2
#MD.Type nomd
#MD.maxIter 1
#MD.TimeStep 1.0
#MD.Opt.criterion 0.0003
######cell and geometry optimization############
MD.Type OptC5 # Nomd|Opt|DIIS|OptC|RFC5|BFGS|RF|EF
MD.Opt.DIIS.History 5 # default=3 the behavior of quasi Newton methods is controlled by MD.Opt.DIIS.History and MD.Opt.StartDIIS
MD.Opt.StartDIIS 15 # default=5 The geometry optimization steps before starting the DIIS-type method is performed by the steepest decent method.
MD.Opt.EveryDIIS 10000 # default=10
MD.maxIter 200 # default=1
MD.Opt.criterion 1.0e-5 # default=1.0e-4 (Hartree/bohr)
#MD.applied.pressure 10.0 # in GPa, default=0 To perform the optimization of enthalpy
#MD.applied.pressure.flag 1 1 1 # default=1 1 1 direction of x y z, better choose orthorhombic crystal systems
################vdW correction#################
scf.dftD on # on|off, default=off
version.dftD 3 # 2|3, default=2
DFTD3.damp bj # zero|bj, default=bj
DFTD.Unit AU # Ang|AU
DFTD.rcut_dftD 100.0 # default=100 (DFTD.Unit)
DFTD.cncut_dftD 40 # default=40 (DFTD.Unit)
DFTD.IntDirection 0 0 0 # default=1 1 1 (1:on 0:off),direction x,y,z;DFTD.IntDirection control the vdW interaction between the central cell and the periodic images.
can you help me to check it, why this setting parameters can not get the more accurate interlayer distance value. I have done some test on increasing the "scf.Kgrid" and "scf.energycutoff" or changing "Definition.of.Atomic.Species"(including more orbitals) and different vdW correction method. All those test indicate the interlayer distance is around 4.0A. Therefore, I really can't figure out where is the problem.
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