Ensembles

Available ensembles are the straightforward NVT, NPT and Gibbs, see Input Parameters for details of their configuration. An experimental (ie not fully tested) semi-grand canonical ensemble is available. Also Ostwald ripening can be simulated, see below.

NVT

Activated by setting simulation_type to “NVT” (Default).

NPT

Activated by setting simulation_type to “NPT”. reference_pressure should be set to the imposed pressure.

Gibbs

Activated de facto by setting box_to_box_probability and volume_exchange_probability to a positive value.

Semi-grand canonical ensemble

Activated by setting simulation_type to “SGVT” or the isobaric variant “SGPT”.

The radii of the particles can vary but not the total number, this variation is regulated by a tabulated chemical potential. In addition, if update_chempot_table is set to yes, the chemical potential table is updated according to a goal distribution, the user is expected to re-run the simulation until convergence of the mean distribution to this goal distribution.

Additional input files

table_fit_keffs.dat
Contains parameters to the fit of charges inverse Debye length as a function of inverse Debye length. It also contains data to adjust the inverse Debye length from density and distribution in accordance with the polydisperse cell model.
chempot_table.dat
Contains the table (2-column Radius and value) of chemical potential. Note: Overwritten at the end of the simulation if``update_chempot_table`` is set to yes
distrib_goal.dat
Contains a table of the goal distribution (only necessary if update_chempot_table is set to yes).

Additional output files

pcmc_kappa.dat
Inverse Debye length as a function of step.
pcmc_meandist.dat
Mean size distribution over a run.
pcmc_intermpsd.dat
Size distribution as a function of step. (2-column (R, D) size distribution separated by a ‘&’ line, grace understands it).
chempot_table.dat.old
If update_chempot_table is set to yes, it is a copy of chempot_table.dat.

Additional parameters

Additional parameters are added in a section [sgc] in the config file.

particle_resize_prob
Probability to make a particle resize move. Default is 0.
particle_resize_cvf_prob
Probability to make a particle resize move at constant volume fraction (involving two particles). Default is 0.
big_step_kappa_update
Activates the periodic update of the inverse Debye length. Default is yes.
kappa_update_period
Period of the update of the inverse Debye length. Default is 100. Desactivate with a negative value.
min_radius
Minimum reachable particle radius. Default is 2.0.
max_radius
Maximum reachable particle radius. Default is 30.0.
min_radius_psd
Minimum particle radius of the calculated size distribution. Default is 2.0.
max_radius_psd
Minimum particle radius of the calculated size distribution. Default is 30.0.
psd_dr
Interval of the calculated size distribution. Default is 0.1.
update_kappa_radius_resize
Activates the update of the inverse Debye length for each particle resize. Default is no

Ostwald ripening

Activated by setting simulation_type to “Ostwald-VT” or “Ostwald-PT”.

The particles can exchange “monomers” with a finite bulk. This is meant to be an out-of-equilibrium simulation, the interpretation in the context of MC simulations is left to the user.

Additional input files

table_fit_keffs.dat
Contains parameters to the fit of charges inverse Debye length as a function of inverse Debye length. It also contains data to adjust the inverse Debye length from density and distribution in accordance with the polydisperse cell model.

Additional output files

pcmc_kappa.dat
Inverse Debye length as a function of step.
pcmc_eq_rmean.dat

Mean radius and others as a function of step.

step mean radius critial raidus variance of radius moves/cycle/(nb of particles)

The last column may be useful to recalculate an effective step because the nb of particles is variable.

pcmc_meandist.dat
Mean size distribution over a run.
pcmc_intermpsd.dat
Size distribution as a function of step. (2-column (R, D) size distribution separated by a ‘&’ line, grace understands it).
pcmc_psdrel.dat
Relative size distribution as a function of step
pcmc_dFormvsdEint.dat

Average energies of dissolution/precipitation as a function of radius.

R ΔE_int_diss ΔF_form_diss ΔE_int_prec ΔF_form_prec

Additional parameters

Additional parameters are added in a section [sgc] in the config file.

particle_bulk_exchange_prob
Probability to make move that exchange monomers between the solid particles and the bulk. Default is 0.
particle_bulk_formation_prob
Probability to make move that precipitates/dissolves a particle from/to the bulk. Default is 0.
total_number_monos
Sets the total number of monomers. Default is 300 000.
initial_number_dissolved_monos
Sets the initial number of dissolved monomers if a positive value is given. It takes over total_number_monos.
minimum_monos_exchange
Minimum of monomers that can be exchanged with the bulk. Default is 10.
maximum_monos_exchange
Maximum of monomers that can be exchanged with the bulk. Default is 100.
minimum_monos_particles
Minimum of monomers taken/given from/to the bulk for a precipitation/dissolution. Default is 10.
maximum_monos_particles
Maximum of monomers taken/given from/to the bulk for a precipitation/dissolution. Default is 100.
gamma0
Surface tension (in kT) for an infinite radius and a neutral surface. Default is 17.
tolman_length
Sets the Tolman length. Default is 1.0.
gamma_doublelayer_inf
Sets the double layer contribution to the surface tension for an infinite radius. Default is -0.633177.
gamma_doublelayer_slope
Sets the slope regarding 1/R of the double layer contribution to the surface tension. Default is 1.535432.
big_step_kappa_update
Activates the periodic update of the inverse Debye length. Default is yes.
kappa_update_period
Period of the update of the inverse Debye length. Default is 100. Desactivate with a negative value.
min_radius_psd
Minimum particle radius of the calculated size distribution. Default is 2.0.
max_radius_psd
Minimum particle radius of the calculated size distribution. Default is 30.0.
psd_dr
Interval of the calculated size distribution. Default is 0.1.
update_kappa_radius_resize
Activates the update of the inverse Debye length for each particle resize. Default is no.
min_radius_gamma
Below that value. the surface tension is constant. Default is 0.0
pseudo_kinetics
Toggles the use of a kinetic factor for exchanges with bulk. Not really working. Default is no.
implicits_maximum_size
Maximum monomer size of the smallest particles. Default is 100.
implicits_minimum_size
Minimum monomer size of the smallest particles. Default is 2.
solid_density
Density of the solid phase (ie, particles). Default is 22.96 nm^-3.
pKs
Decimal logarithm of the solubility constant. Default is 2.7.
finite_monomer_reservoir
If set to no, the bulk is considered infinite. Default is yes.
bulk_exchange_create_destroy
Toggles the creation/deletion of particles in the main exchange move. Default is no.