I can not get the equlibrium lattice constants using openmx3.2

Top Page > Browsing

I can not get the equlibrium lattice constants using openmx3.2

Date: 2007/05/30 00:37
Name: hugh: Dear OPENMX developmenters,

I performed some calculations of the bulk platinum (Pt) on a series of different lattice constants using the PAO-8.0 and Pseudopotential provided by this web, but I can not get equlibrium lattice constants. The total energy change linearly with lattice volumes! I can get the satisfactory using other PW methods. Have the pseduopotential and basis sets of Pt in the database been well verified? Here, I attach my input file. Please you tell me how to obtain a smooth E-V cuve for Pt? Thanks in advance!

Best regards,
Hugh

========================
#
# File Name
#

System.CurrrentDirectory ./ # default=./
System.Name Pt
level.of.stdout 1 # default=1 (1-3)
level.of.fileout 1 # default=1 (1-3)

#
# restart using a restart file, *.rst
#

scf.restart off # on|off,default=off

#
# Definition of Atomic Species
#

Species.Number 1
<Definition.of.Atomic.Species
Pt Pt8.0-s2p2d1 Pt_GGA
Definition.of.Atomic.Species>

#
# Atoms
#

Atoms.Number 1
Atoms.SpeciesAndCoordinates.Unit Ang # Ang|AU
<Atoms.SpeciesAndCoordinates # Unit=Ang.
1 Pt 0.00000 0.00000 0.00000 5.0 5.0
Atoms.SpeciesAndCoordinates>
Atoms.UnitVectors.Unit Ang # Ang|AU
<Atoms.UnitVectors # unit=Ang.
0.00000 1.96000 1.96000
1.96000 0.00000 1.96000
1.96000 1.96000 0.00000
Atoms.UnitVectors>

#
# SCF or Electronic System
#

scf.XcType GGA-PBE # LDA|LSDA-CA|LSDA-PW
scf.SpinPolarization off # On|Off
scf.ElectronicTemperature 300.0 # default=300 (K)
scf.energycutoff 150.0 # default=150 (Ry)
scf.Ngrid 32 32 32 # n1, n2, and n3 for a-, b-, and c-axes
scf.maxIter 100 # default=40
scf.EigenvalueSolver band # Recursion|Cluster|Band
scf.lapack.dste dstevx # dstegr|dstedc|dstevx, default=dstegr
scf.Kgrid 9 9 9 # means 4x4x4
scf.Mixing.Type rmm-diisk # Simple|Rmm-Diis|Gr-Pulay
scf.Init.Mixing.Weight 0.010 # default=0.30
scf.Min.Mixing.Weight 0.010 # default=0.001
scf.Max.Mixing.Weight 0.200 # default=0.40
scf.Mixing.History 6 # default=5
scf.Mixing.StartPulay 12 # default=6
scf.criterion 1.0e-9 # default=1.0e-6 (Hartree)
scf.system.charge 0.0 # default=0.0

#
# 1D FFT
#

1DFFT.NumGridK 900 # default=900
1DFFT.NumGridR 900 # default=900
1DFFT.EnergyCutoff 3600.0 # default=3600 (Ry)

#
# Orbital Optimization
#

orbitalOpt.Method off # Off|Unrestricted|Restricted
orbitalOpt.InitCoes Symmetrical # Symmetrical|Free
orbitalOpt.initPrefactor 0.1 # default=0.1
orbitalOpt.scf.maxIter 15 # default=12
orbitalOpt.MD.maxIter 7 # default=5
orbitalOpt.per.MDIter 20 # default=1000000
orbitalOpt.criterion 1.0e-4 # default=1.0e-4 (Hartree/borh)^2

#
# output of contracted orbitals
#

CntOrb.fileout off # on|off, default=off
Num.CntOrb.Atoms 1 # default=1
<Atoms.Cont.Orbitals
1
Atoms.Cont.Orbitals>

#
# SCF Order-N
#

orderN.HoppingRanges 6.0 # default=5.0 (Ang)
orderN.NumHoppings 1 # default=2

#
# MD or Geometry Optimization
#

MD.Type nomd # Nomd|Opt|DIIS|NVE|NVT_VS|NVT_NH
MD.Opt.DIIS.History 3 # default=7
MD.maxIter 1 # default=1
MD.TimeStep 0.5 # default=0.5 (fs)
MD.Opt.criterion 2.0e-5 # default=1.0e-4 (Hartree/bohr)

Page: [1]

Re: I can not get the equlibrium lattice constants using openmx3.2 ( No.1 )

Date: 2007/05/31 22:21
Name: T.Ozaki

Hi,

This might be related to the overcompleteness of basis functions as
I wrote in http://www.openmx-square.org/forum/patio.cgi?mode=view&no=286
The cutoff radius of 8.0 a.u. seems to be longer than an appropriate
value that we usually used for the Pt bulk.

Could you reduce the cutoff radius and gradually increase it to see
what happens ?

Best regards,

TO

Re: I can not get the equlibrium lattice constants using openmx3.2 ( No.2 )

Date: 2007/06/01 23:19
Name: hugh

Dear T.Ozaki,

Sorry, I still cannot get a satisfactory results and the total energy still change linearly with volume, although I used the smaller the cutoff radius (6.0 and 7.0). The E-V relation is listed as following:
====================================
88.257439282461 -49.034112753389
95.527890846646 -48.729943767457
104.766412761106 -48.347540547190
107.973328593666 -48.216722581672
====================================

Using other PW codes based on GGA, the equlibrium lattice constant is 3.98 Angstrom (volume: ~108 bohr^3), which agrees well other theoretical work. Are there other reasons resulting in this problem?

Regards,
Hugh

Re: I can not get the equlibrium lattice constants using openmx3.2 ( No.3 )

Date: 2007/06/02 10:40
Name: T.Ozaki

Hi,

My result by OpenMX3.2 is as follows:

3.86 -120.505206398483
3.90 -120.509713310915
3.92 -120.511453649270
3.94 -120.513004977916
3.96 -120.514254468704
3.98 -120.515232979293
4.02 -120.516544625037
4.06 -120.516976082650
4.10 -120.516797197965
4.14 -120.516005384550

The caculated equilibrium lattice constant is 4.06 Ang which is
3.6% larger than the experimental value (3.92 Ang).

For your convenience, my input file is attached below.

Regards,

TO

#
# File Name
#

System.CurrrentDirectory ./ # default=./
System.Name pt
level.of.stdout 1 # default=1 (1-3)
level.of.fileout 1 # default=1 (1-3)
DATA.PATH ../DFT_DATA06

#
# Definition of Atomic Species
#

Species.Number 1
<Definition.of.Atomic.Species
Pt Pt7.0-s2p2d1 Pt_PBE
Definition.of.Atomic.Species>

#
# Atoms
#

Atoms.Number 1
Atoms.SpeciesAndCoordinates.Unit FRAC # Ang|AU
<Atoms.SpeciesAndCoordinates
1 Pt 0.0000 0.0000 0.0000 9.0 9.0
Atoms.SpeciesAndCoordinates>

Atoms.UnitVectors.Unit Ang # Ang|AU
<Atoms.UnitVectors
1.9900 1.9900 0.0000
0.0000 1.9900 1.9900
1.9900 0.0000 1.9900
Atoms.UnitVectors>

#
# SCF or Electronic System
#

scf.XcType GGA-PBE # LDA|LSDA-CA|LSDA-PW
scf.SpinPolarization off # On|Off
scf.partialCoreCorrection On # On|Off
scf.ElectronicTemperature 300.0 # default=300 (K)
scf.energycutoff 200.0 # default=150 (Ry)
scf.Ngrid 20 20 20
scf.maxIter 100 # default=40
scf.EigenvalueSolver band # Recursion|Cluster|Band
scf.Kgrid 7 7 7 # means n1 x n2 x n3
scf.Mixing.Type rmm-diisk # Simple|Rmm-Diis|Gr-Pulay
scf.Init.Mixing.Weight 0.30 # default=0.30
scf.Min.Mixing.Weight 0.001 # default=0.001
scf.Max.Mixing.Weight 0.400 # default=0.40
scf.Mixing.History 7 # default=5
scf.Mixing.StartPulay 13 # default=6
scf.criterion 1.0e-9 # default=1.0e-6 (Hartree)

#
# 1D FFT
#

1DFFT.NumGridK 900 # default=900
1DFFT.NumGridR 900 # default=900
1DFFT.EnergyCutoff 3600.0 # default=3600(Ry)

#
# MD or Geometry Optimization
#

MD.Type nomd # Nomd|Opt|DIIS|NVE|NVT_VS|NVT_NH
MD.maxIter 1 # default=1
MD.TimeStep 1 # default=0.5 (fs)
MD.Opt.criterion 1.0e-5 # default=1.0e-4 (Hartree/bohr)

Re: I can not get the equlibrium lattice constants using openmx3.2 ( No.4 )

Date: 2007/06/04 22:15
Name: hugh

Dear T.Ozaki,

Thank you for your input file. Yes, now I can get a smooth E-V curve according to your inpu t file. I also know why the strange phenomenon appears in my calculation. Maybe the main problem is that in my input file I used old PAO (04 version) file, but the VPS files is new (06 version), and the valence electrons should be 18 in 06 VPS and PAO files. I am very sorry for my ambiguous on using it. Now My new question is how to further optimize the lattice constant. I means that a=4.06 is too large comparing with other computational methods. According to your experience, which should I further modify parameters in my input files?

Thanks again for your great help!

Regards,
Hugh

Re: I can not get the equlibrium lattice constants using openmx3.2 ( No.5 )

Date: 2007/06/08 09:03
Name: T.Ozaki

Hi,

Such a difference can be attributed to basis set and pseudopotential.
To check this, firstly the basis set should be checked by systematically
increasing the cutoff radius and the number of basis funtions.
If this is not the case, the pseudopotential should be optimized.

Best regards,

TO

Page: [1]