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General Questions and Answers / Re: How to optimize the bulk lattice
« on: March 23, 2009, 11:43 »
Dear Nordland,
My input file for optimizating rutile bulk is :
###############################
from stress_optimizers import *
import ATK; ATK.setVerbosityLevel(1)
from ATK.KohnSham import *
# Select Bravais lattice and define lattice constants
bravais_lattice = BodyCenteredTetragonal(
a=4.594000 * Angstrom,
c=2.959000 * Angstrom
)
# Define bulk elements and unit cell coordinates
elements = [Titanium, Oxygen]
coordinates = [[ 0. , 0. , 0. ],
[ 0.69520000, 0.30480000, 0. ]]
# Set up bulk configuration
bulk_configuration = BulkConfiguration(
bravais_lattice,
elements,
fractional_coordinates=coordinates
)
nlPrint(bulk_configuration)
method = KohnShamMethod(brillouin_zone_integration_parameters = brillouinZoneIntegrationParameters((5,5,7)),
basis_set_parameters = basisSetParameters())
opt_conf = calculateOptimizedBulkConfiguration(bulk_configuration, method, runtimeParameters(1))
################################
I noticed from the output, the initially calculated stress is very large:
# Stresses
# Stress (A) = -277.951887706 eV/Ang**3
# Stress (C) = -277.700861096 eV/Ang**3
I think my lattices (4.954, 2.959) are not too far from the experimental ones. Is this stress reliable? Or do I make something wrong?
Regards,
Frsy
My input file for optimizating rutile bulk is :
###############################
from stress_optimizers import *
import ATK; ATK.setVerbosityLevel(1)
from ATK.KohnSham import *
# Select Bravais lattice and define lattice constants
bravais_lattice = BodyCenteredTetragonal(
a=4.594000 * Angstrom,
c=2.959000 * Angstrom
)
# Define bulk elements and unit cell coordinates
elements = [Titanium, Oxygen]
coordinates = [[ 0. , 0. , 0. ],
[ 0.69520000, 0.30480000, 0. ]]
# Set up bulk configuration
bulk_configuration = BulkConfiguration(
bravais_lattice,
elements,
fractional_coordinates=coordinates
)
nlPrint(bulk_configuration)
method = KohnShamMethod(brillouin_zone_integration_parameters = brillouinZoneIntegrationParameters((5,5,7)),
basis_set_parameters = basisSetParameters())
opt_conf = calculateOptimizedBulkConfiguration(bulk_configuration, method, runtimeParameters(1))
################################
I noticed from the output, the initially calculated stress is very large:
# Stresses
# Stress (A) = -277.951887706 eV/Ang**3
# Stress (C) = -277.700861096 eV/Ang**3
I think my lattices (4.954, 2.959) are not too far from the experimental ones. Is this stress reliable? Or do I make something wrong?
Regards,
Frsy