Dear all
In case phonon calculation of methane, I got the following
frequencies.
-5167.7290 -1034.5158 -608.1908 -608.1117 -67.8524 -67.8411
-23.1827 -0.3640 -0.0552 0.1225 1253.0287 2962.9873
2989.7891 3311.1902 3311.2054
Again in *.FC calculation, forces on the methane atoms for +x and -x
displacement of atom no-1 are as follows.
-----------------------------------------
For -x displacement
1 1.301549 -0.000023 0.000003
2 -0.750276 0.000005 0.000000
3 0.058844 0.004557 0.000000
4 -0.670075 -0.000003 -0.000001
5 0.058833 -0.004936 -0.000001
For +x displacement
1 -1.301586 -0.000026 -0.000002
2 0.669685 0.000006 0.000000
3 -0.058834 0.004552 0.000000
4 0.749907 -0.000003 -0.000001
5 -0.058837 -0.004934 -0.000001
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Here forces on 2nd and 4th atom have difference force.
Are these will be same in + and - displacement of the atom?
For *.FC calculation may input file as given.
-----------------------------------------------------
# GGA
# Phonon 32 atom
# Methane
SystemName Bond length calculation # Descriptive name of the system
SystemLabel Methane # Short name for naming files
# Output options
LongOutput true
# Species and atoms
%block ChemicalSpeciesLabel
1 6 C
2 1 H
%endblock ChemicalSpeciesLabel
NumberOfSpecies 2
NumberOfAtoms 5
WriteKpoints true
PAO.Basis<basis.fdf
LatticeConstant 1 Ang
%block LatticeVectors
10.0009892951 -0.000000035 -0.000000083
-0.000000035 10.0009892778 -0.000000094
-0.000000083 -0.000000094 10.0000562322
%endblock LatticeVectors
Meshcutoff 500 Ry
Kgridcutoff 50.0 Ang
xc.functional GGA # Exchange-correlation functional
xc.authors PBE
MaxSCFIterations 500 # Maximum number of SCF iter
DM.UseSaveDM true
MD.TypeOfRun FC # Type of dynamics:
MD.NumCGsteps 500
DM.Tolerance 0.1d-4
DM.Require.Energy.Convergence true
DM.Energy.Tolerance 0.1d-4 eV
#Atomic coordinates
AtomicCoordinatesFormat Ang
%block AtomicCoordinatesAndAtomicSpecies
05.00000000 05.00000000 05.00000000 1
03.89716380 05.00000000 05.00000000 2
05.00000000 03.89716380 05.00000000 2
06.1028361 05.00000000 05.00000000 2
05.00000000 06.1028361 05.00000000 2
%endblock AtomicCoordinatesAndAtomicSpecies
------------------------------------
Please help me what is going wrong.
Thanking you.
Regards
Saikat Paik
IIT Kanpur
Mtech
Mechanical Engineering.
