Thermodynamic stability (stability)

Calculation of spinodal and binodal

Classes:

RootResultTotal	Modified root result
StabilityBase(collection)	Base class for stability
Spinodals(collection)	Methods for calculation locations of spinodal
Binodals(collection)	Routines to calculate binodal.

Functions:

get_spinodal(collection, build_phases, idx)

Locate spinodal point for a given pair of phases.

class lnpy.stability.RootResultTotal

Bases: dict

Modified root result

lnpy.stability.get_spinodal(collection, build_phases, idx, idx_nebr=None, efac=1.0, dlnz=0.5, dfac=1.0, vmin=0.0, vmax=100000.0, ntry=20, step=None, nmax=20, ref=None, build_kws=None, close_kws=None, solve_kws=None)

Locate spinodal point for a given pair of phases.

Parameters:

• ref (lnPiMasked)

• collection (lnPiCollection) – initial estimates to work from. Function assumes collection is in lnz sorted order

• idx, idx_nebr (int) – from/to phase id

• lnz_in (list) – list with value of static chem pot, and None for variable. e.g., lnz_in=[None,0.0] implies lnz[0] is variable, and lnz[1]=0.0

• efac (float, optional) – cutoff value for spinodal

• dlnz (float, optional) – factor to kick back if collection doesn’t already have left and right bounds

• vmin (float, optional) – Value denoting vmin, i.e., value of free energy difference phase does not exist.

• vmax (float, optional) – value indicating no transition, but phase idx is present.

• ntry (int, default 20) – number of times to try kicking forward/backwards to find bracket

• step (int or None, default None) – if +1, step forward if -1, step backward if None, try to determine step

• nmax (int, default 20) – max number of steps to refine bracket

• build_phases (callable(), optional) – Function to create Phases. Default is that from get_default_phasecreator

• build_kws (dict, optional) – extra arguments to build_phases

• close_kws (dict, optional) – arguments to numpy.allclose()

• solve_kws (dict, optional) – extra arguments to scipy.optimize.brentq()

Returns:

• out (lnPiCollection object at spinodal point)

• r (object) – Info object

class lnpy.stability.StabilityBase(collection)

Bases: object

Base class for stability

Parameters:

collection (lnPiCollection) – Used to bracket the location limit of stability

Attributes:

parent	Accessor to parent lnPiCollection object
items	Access to the underlying data
access	View (lnpy.lnpiseries.lnPiCollection) of stability
appender	View of access to be appended to parent

Methods:

append_to_parent([sort, copy_stability])

New collection with spinodal data appended to parent.

property parent

Accessor to parent lnPiCollection object

property items

Access to the underlying data

access

View (lnpy.lnpiseries.lnPiCollection) of stability

property appender

View of access to be appended to parent

append_to_parent(sort=True, copy_stability=True)

New collection with spinodal data appended to parent.

class lnpy.stability.Spinodals(collection)

Bases: StabilityBase

Methods for calculation locations of spinodal

Methods:

__call__(phase_ids, build_phases, *[, ...])

Parameters: phase_ids (int, or sequence) -- Phase ids to calculate spinodal for. If int, then find spinodals for phases

__call__(phase_ids, build_phases, *, inplace=True, ref=None, build_kws=None, force=False, as_dict=True, unstack=None, raise_unconverged=True, **kwargs)

Parameters:

• phase_ids (int, or sequence) – Phase ids to calculate spinodal for. If int, then find spinodals for phases range(phase_ids).

• build_phases (callable()) – Factory function to build phases. This should most likely be an instance of lnpy.segment.BuildPhasesBase

• ref (lnPiMasked, optional)

• build_kws (dict, optional) – optional arguments to build_phases

• inplace (bool, default True) – if True, add spinodal inplace, otherwise return spinodal object

• force (bool, optional) – if True, force recalculation of spinodal if already set inplace. Otherwise return already calculated values

• as_dict (bool, default True) – if True, return dict of form {phase_id[0] : phases object, …}.

• unstack (bool, optional) – if passed, create lnPiCollection objects with this unstack value. If not passed, use unstack parameter from parent object

• raise_unconverged (bool, default True) – If True, raise error if calculation does not converge.

• **kwargs – Extra argument to get_spinodal() function

Returns:

out (dict or lnPiCollection, optional) – if inplace, return self. if not inplace, and as dict, return dict, else return lnpy.lnpiseries.lnPiCollection with phase_id in index

class lnpy.stability.Binodals(collection)

Bases: StabilityBase

Routines to calculate binodal.

Methods:

__call__(phase_ids, build_phases, *[, ...])

Parameters: phase_ids (int, or sequence) -- Phase ids to calculate binodal for. If int, then find binodal for phases

__call__(phase_ids, build_phases, *, inplace=True, spinodals=None, ref=None, build_kws=None, force=False, as_dict=True, unstack=None, raise_unconverged=True, **kwargs)

Parameters:

• phase_ids (int, or sequence) – Phase ids to calculate binodal for. If int, then find binodal for phases range(phase_ids).

• build_phases (callable()) – Factory function to build phases

• inplace (bool, default True) – if True, add binodal inplace, otherwise return spinodal object

• spinodals (optional) – if not passes, then use parent.spinodal Used for bounding binodal

• ref (lnPiMasked, optional)

• build_kws (dict, optional) – optional arguments to build_phases

• force (bool, optional) – if True, force recalculation of spinodal if already set inplace. Otherwise return already calculated values

• as_dict (bool, default True) – if True, return dict of form {phase_id[0] : phases object, …}

• unstack (bool, optional) – if passed, create lnPiCollection objects with this unstack value. If not passed, use unstack parameter from parent object

• raise_unconverged (bool, default True) – If True, raise error if calculation does not converge.

• **kwargs – Extra argument to get_spinodal() function

Returns:

out (object) – if inplace, return self if not inplace, and as dict, return dict, else return lnPiCollection with phase_id in index