In this work, we showcase SGTPy,
a Python open-source code developed
to calculate interfacial properties (interfacial concentration profiles
and interfacial or surface tension) for pure fluids and fluid mixtures.
SGTPy employs the Square Gradient Theory (SGT) coupled to the Statistical
Associating Fluid Theory of Variable Range employing a Mie potential
(SAFT-VR-Mie). SGTPy uses standard Python numerical packages (i.e.,
NumPy, SciPy) and can be used under Jupyter notebooks. Its features
are the calculation of phase stability, phase equilibria, interfacial
properties, and the optimization of the SGT and SAFT parameters for
vapor–liquid, liquid–liquid and vapor–liquid–liquid
equilibria for pure fluids and multicomponent mixtures. Phase equilibrium
calculations include two-phase and multiphase flash, bubble and dew
points, and the tangent plane distance. For the computation of interfacial
properties, SGTPy incorporates several options to solve the interfacial
concentration, such as the path technique, an auxiliary time function,
and orthogonal collocation. Additionally, the SGTPy code allows the
inclusion of subroutines from other languages (e.g., Fortran, and
C++) through Cython and f2py Python tools, which opens the possibility
for future extensions or recycling tested and optimized subroutines
from other codes. Supporting Information includes a review of the
theoretical expressions required to couple SAFT-VR-Mie equation of
state with the SGT. The use and capabilities of SGTPy are illustrated
through step by step examples written on Jupyter notebooks for the
cases of pure fluids and binary and ternary mixtures in bi- and three-
phasic equilibria. The SGTPy code can be downloaded from .