starrynight.cfg

#Default Starrynight config file
# Nb: with libconfig library http://www.hyperrealm.com/libconfig/libconfig_manual.html

LOGFILE="Efield.log"

# Simulation Temperature - beta=1/T  T=temperature of the lattice, in units of k_B
T: 300 # 300 #Integar value, Kelvin

# Lattice size
X=20
Y=20
Z=28

#{ random, ferroelectric, buckled, antiferro_wall, ferro_wall, antiferro_slip, spectrum, slab_delete};
InitialLattice="antiferro_wall"

# Applied Electric field
Efield: 
{
 #x= 0.02 # Calculated value for 10M V/m (1V over 100nm) applied to 2.29 Debye dipole
 #x = 10.0 # test for homogenous alignment of dipoles
 #x=1.0
 #y=0.02
 x=0.0
 y=0.0
 z=0.0
}

DipoleCutOff: 3 #Cutoff for dipole-dipole interaction; in lattice units 
#(Nb: integar, might want to make this floating point to allow for more spherical like discretised shapes)

ConstrainToX: false # constrain dipoles to <100> (Cartessian axes) for moves

# HAMILTONIAN

# Elastic coupling constant for dipole moving within cage (units k_B T)
# Positive values try and align dipoles along diagonal
# Negatives values try and align dipoles towards edges (faces of cube)
# K: -2.0 # sufficies to force ^/> alignment of dipoles, much larger domains
# K: +2.0 # alignment /\/\/\/\ destroys ferroelectric response?
K: 0.0 # KISS

# Dipole coupling constant list (lattice = 1 unit, units k_B T)
# Made into a solid solution with these...
Dipoles    = [ 1.0, 0.0, 0.0];
Prevalence = [ 1.0, 0.0, 0.0]; 

# From NanoLetters 2014, Dipole-Dipole for Methyl-Ammonia is ~26 meV. i.e. 1 kBT
# Dipoles = 1.0
# If we shield effect by dielectric const of 25 (static dielectric, from ion harmonic response), this becomes 
# Dipoles = 0.04
# If we shield effect by dielectric const of 6 (optical dielectric constant), this becomes
# Dipoles=0.18

# CageStrain - local dotproduct interaction energy,
# assumes only 6 nearest neighbours (+x/-x/+y/-y/+z/-z) interact w/ this strength
# units of kBT @ 300 K
CageStrain = 1.0 

# MC steps parameters

# Number of megasteps, i.e. log files
MCMegaSteps: 20 
# Number of equlibriation steps, before data collection
MCEqmSteps: 5 

# Multiplier for each MC Mega Step (i.e. on avg. this number of MC moves per site per datapoint)
MCMoves: 200.0 # 0000.0 #Must be floating point!

# Simulation display / calculation flags 

DisplayDumbTerminal: true 
CalculateRecombination: false #And display...
CalculateRadialOrderParameter: true #And display...

CalculatePotential: true 
CalculateEfield: false

SaveDipolesPNG: false
SaveDipolesSVG: false 
SaveDipolesXYZ: false
SavePotentialCube: true