Thermo Files

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Thermo file blocks contain output variables that are computed during an SCFT calculation. Such blocks may appear either as standalone files, which can be created by the WRITE_THERMO command, or as sections of other file types.

Suppose that a file named 'input' contains a thermo file block that is the only data in this file. One may parse this file by entering the Python commands

from pscfpp.output import *
thermo = Thermo('input')

In this case, the Thermo constructor opens and parses the contents of the file whose name is passed as an argument, and returns an instance of class Thermo that contains the contents of that file. Here, the resulting object is assigned to a variable named 'thermo'. This name is used in all of the following examples to represent a Thermo object that contains the contents of a thermo file block.

The values of output variables that are reported in a thermo file block can be accessed using the dot syntax for the attributes of the Thermo object similar to that used for the Param object. For example

thermo.fHelmholtz

is the value of the variable 'fHelmholtz' reported in the thermo file block, which is the Helmholtz free energy per monomer in thermal energy units. A similar syntax is used to access the attributes 'pressure', 'fIdeal' and 'fInter', each of which is stored as a corresponding floating point data attribute of object thermo.

A Thermo object may have attributes named 'polymers', 'solvents', 'cellParams', 'stress', and/or 'environmentStress' if the thermo file block contains the corresponding elements. Each of these attributes, when present, is a Python list, with elements that can be accessed using the square bracket syntax. For example, if thermo contains the contents of the thermo block produced by a pscf_pc or pscf_pg simulation of a periodic system, the quantity

thermo.cellParams[0]

is equal to the final value of the first cell parameter for the crystal system of interest.

Attributes of a Thermo object named polymers or solvents are lists in which each element is an instance of a class pscfpp.output.Species that has float attributes phi (volume fraction) and mu (chemical potential). The quantity

thermo.polymers[0].phi

is thus the volume fraction of the first polymer species in a mixture, while

thermo.polymers[0].mu

is the corresponding chemical potential. In systems that contain one or more solvent species, an analogous syntax is used for solvent species as elements of a list thermo.solvents

The string representation of a Thermo object is a multi-line string formatted like the thermo file block from which the object was created. This string representation of Thermo object named thermo is given by the expression str(thermo), and can be printed to screen using print(thermo).

Homogeneous comparison

In r1d, one can use the COMPARE_HOMOGENEOUS command to write data to a thermo file that compares the results to a corresponding homogeneous phase. This block of the thermo file is read into a Thermo object in the form of two attributes: thermo.homogeneous and thermo.homogeneousSpecies. The former is a Python dictionary containing the first block of homogeneous data, where each value is stored with a key equal to the name of the property as written in the PSCF output. For example, the property labeled 'f (homo)' can be accessed by

thermo.homogeneous['f (homo)']

The attribute thermo.homogeneousSpecies is a list of dictionaries, one for each species, where each member of the list corresponds to a single species and the data values for each species are stored with keys that match the name given in the thermo output. For example, the 'deltaV' property of species 0 can be accessed by

thermo.homogeneousSpecies[0]['deltaV']

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