Hi,
Let me ask a silly question: did you optimized your CH_4 before the
FC calculation ?.
At first sight your running parameters look pretty conservative to
me, they should be fine. However those forces you mention must be
the same (but for sign or course).
What is that "PAO.Basis<basis.fdf" ?. No complaints about it ?.
According to the manual it should be "%block PAO.Basis < basis.fdf".
Regards,
Roberto
On Fri, 2 Nov 2012, [email protected] wrote:
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
------------------------------------------
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.
