add changelog

feos-org · prehner · Apr 14, 2023 · Mar 22, 2023 · Mar 24, 2023 · Mar 25, 2023
commit b44014403b06b05c433b4d4f6055c981fc1c4440
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -5,6 +5,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Changed
+- Changed the internal implementation of the association contribution to accomodate more general association schemes. [#150](https://github.com/feos-org/feos/pull/150)
+- To comply with the new association implementation, the default values of `na` and `nb` are now `0` rather than `1`. Parameter files have been adapted accordingly. [#150](https://github.com/feos-org/feos/pull/150)
 
 ## [0.4.2] - 2023-03-20
 - Python only: Release the changes introduced in `feos-core` 0.4.1 and `feos-dft` 0.4.1.

diff --git a/docs/theory/models/association.md b/docs/theory/models/association.md
@@ -30,7 +30,7 @@ The analytic Hessian is
 
 $$H_{\alpha\beta}=-\frac{\delta_{\alpha\beta}}{X_\alpha^2}-\rho_\beta\Delta^{\alpha\beta}$$
 
-with the dirac delta function $\delta_{\alpha\beta}$. However, [Michelsen 2006](https://pubs.acs.org/doi/full/10.1021/ie060029x) shows that it is beneficial to use
+with the Kronecker delta $\delta_{\alpha\beta}$. However, [Michelsen 2006](https://pubs.acs.org/doi/full/10.1021/ie060029x) shows that it is beneficial to use
 
 $$\hat{H}_{\alpha\beta}=-\frac{\delta_{\alpha\beta}}{X_\alpha}\left(1+\sum_\beta\rho_\beta X_\beta\Delta^{\alpha\beta}\right)-\rho_\beta\Delta^{\alpha\beta}$$
 

diff --git a/src/association/mod.rs b/src/association/mod.rs
@@ -77,7 +77,7 @@ impl fmt::Display for AssociationRecord {
             write!(f, ", na={}", self.na)?;
         }
         if self.nb > 0.0 {
-            write!(f, ", nb={})", self.nb)?;
+            write!(f, ", nb={}", self.nb)?;
         }
         if self.nc > 0.0 {
             write!(f, ", nc={}", self.nc)?;

diff --git a/src/association/python.rs b/src/association/python.rs
@@ -11,6 +11,7 @@ pub struct PyAssociationRecord(pub AssociationRecord);
 #[pymethods]
 impl PyAssociationRecord {
     #[new]
+    #[pyo3(signature = (kappa_ab, epsilon_k_ab, na=0.0, nb=0.0, nc=0.0))]
     fn new(kappa_ab: f64, epsilon_k_ab: f64, na: f64, nb: f64, nc: f64) -> Self {
         Self(AssociationRecord::new(kappa_ab, epsilon_k_ab, na, nb, nc))
     }