The FeOs package provides Rust implementations of different equation of state and Helmholtz energy functional models and corresponding Python bindings.
```python from feos.eos import EquationOfState, State from feos.pcsaft import PcSaftParameters
parameters = PcSaftParameters.from_json(['methanol'], 'parameters.json') eos = EquationOfState.pcsaft(parameters)
criticalpoint = State.criticalpoint(eos)
p = criticalpoint.pressure()
t = criticalpoint.temperature
print(f'Critical point for methanol: T={t}, p={p}.')
terminal
Critical point for methanol: T=531.5 K, p=10.7 MPa.
```
The following models are currently published as part of the FeOs framework
|name|description|eos|dft|
|-|-|:-:|:-:|
|pcsaft|perturbed-chain (polar) statistical associating fluid theory|✓|✓|
|gc-pcsaft|(heterosegmented) group contribution PC-SAFT|✓|✓|
|pets|perturbed truncated and shifted Lennard-Jones mixtures|✓|✓|
|uvtheory|equation of state for Mie fluids and mixtures|✓||
The list is being expanded continuously. Currently under development are implementations of ePC-SAFT, a Helmholtz energy functional for the UV theory, and SAFT-VRQ-Mie.
Other public repositories that implement models within the FeOs framework, but are currently not part of the feos Python package, are
|name|description|eos|dft|
|-|-|:-:|:-:|
|feos-fused-chains|heterosegmented fused-sphere chain functional||✓|
In addition to the source code for the Rust and Python packages, this repository contains JSON files with previously published parameters for the different models including group contribution methods. The parameter files can be read directly from Rust or Python.
The crate makes use of generalized (hyper-) dual numbers to generically calculate exact partial derivatives from Helmholtz energy equations of state. The derivatives are used to calculate - equilibrium properties (pressure, heat capacity, fugacity, and many more), - transport properties (viscosity, thermal conductivity, diffusion coefficients) using the entropy scaling approach - critical points and phase equilibria for pure components and mixtures.
In addition to that, utilities are provided to assist in the handling of parameters for both molecular equations of state and (homosegmented) group contribution methods and for the generation of phase diagrams for pure components and binary mixtures.
FeOs uses efficient numerical methods to calculate density profiles in inhomogeneous systems. Highlights include:
- Fast calculation of convolution integrals in cartesian (1D, 2D and 3D), polar, cylindrical, and spherical coordinate systems using FFT and related algorithms.
- Automatic calculation of partial derivatives of Helmholtz energy densities (including temperature derivatives) using automatic differentiation with generalized (hyper-) dual numbers.
- Modeling of heterosegmented molecules, including branched molecules.
- Functionalities for calculating surface tensions, adsorption isotherms, pair correlation functions, and solvation free energies.
Without additional features activated, the command
cargo test --release
will only build and test the core functionalities of the crate. To run unit and integration tests for specific models, run
cargo test --release --features pcsaft
to test, e.g., the implementation of PC-SAFT or
cargo test --release --features all_models
to run tests on all implemented models.
FeOs uses the PyO3 framework to provide Python bindings. The Python package can be installed via pip and runs on Windows, Linux and macOS:
pip install feos
If there is no compiled package for your system available from PyPI and you have a Rust compiler installed, you can instead build the python package from source using
pip install git+https://github.com/feos-org/feos
To compile the code you need the Rust compiler and maturin (>=0.13,<0.14) installed.
To install the package directly into the active environment, use
maturin develop --release --features python
and specify the models that you want to include in the python package as additional features, e.g.
maturin develop --release --features "python pcsaft dft"
for the PC-SAFT equation of state and Helmholtz energy functional. If you want to include all available models, use
maturin develop --release --features "python all_models"
To build wheels, use
maturin build --release --out dist --features "python ..."
For a documentation of the Python API, Python examples, and a guide to the underlying Rust framework check out the documentation.
This software is currently maintained by members of the groups of - Prof. Joachim Gross, Institute of Thermodynamics and Thermal Process Engineering (ITT), University of Stuttgart - Prof. André Bardow, Energy and Process Systems Engineering (EPSE), ETH Zurich
FeOs grew from the need to maintain a common codebase used within the scientific work done in our groups. We share the code publicly as a platform to publish our own research but also encourage other researchers and developers to contribute their own models or implementations of existing equations of state.
If you want to contribute to FeOs, there are several ways to go: improving the documentation and helping with language issues, testing the code on your systems to find bugs, adding new models or algorithms, or providing feature requests. Feel free to message us if you have questions or open an issue to discuss improvements.