feos-org · prehner · Jul 15, 2026 · Dec 15, 2025 · Dec 16, 2025 · Mar 5, 2026
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -6,9 +6,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.4.0] - 2026-07-15
+### Added
+- Included molar weight in `ChemicalRecord`.
+- Added `ripopt` as alternative to `ipopt` for solving the NLP subproblems.
+
+### Packaging
+- Updated to feos v0.10.0.
+
 ## [0.3.3] - 2025-04-14
 ### Fixed
-- Fixed a compatibility problem with the newest version of `num-dual`. [#7](https://github.com/feos-org/feos-campd/pull/7)
+- Fixed a compatibility problem with the newest version of `num-dual`.
 
 ## [0.3.2] - 2025-01-27
 ### Fixed

diff --git a/Cargo.toml b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "feos-campd"
-version = "0.3.3"
+version = "0.4.0"
 authors = ["Philipp Rehner <prehner@ethz.ch>"]
 edition = "2021"
 readme = "README.md"
@@ -12,22 +12,24 @@ keywords = ["process_engineering", "molecular_design", "optimization"]
 categories = ["science"]
 
 [dependencies]
-num-dual = { version = "0.11", features = ["linalg"] }
-quantity = { version = "0.10", features = ["num-dual"] }
-nalgebra = "0.33"
-feos-core = "0.8"
-ndarray = "0.16"
-feos-ad = "0.2"
+num-dual = "0.14"
+quantity = "0.14"
+nalgebra = "0.35"
+feos = { version = "0.10", features = ["pcsaft", "gc_pcsaft"] }
 num-traits = "0.2"
-good_lp = { version = "1.11", default-features = false }
-ipopt = "0.6"
-ipopt-ad = "0.1"
-serde = "1.0"
+good_lp = { version = "1", default-features = false }
+ipopt = { version = "0.6", optional = true }
+ripopt = { version = "0.8", optional = true }
+ipopt-ad = "0.3"
+serde = "1"
 
 [dev-dependencies]
 approx = "0.5"
-itertools = "0.14"
+quantity = { version = "0.14", features = ["approx"] }
+itertools = "0.15"
 
 [features]
-default = ["highs"]
+default = ["highs", "ripopt"]
 highs = ["good_lp/highs"]
+ipopt = ["dep:ipopt", "ipopt-ad/ipopt"]
+ripopt = ["dep:ripopt", "ipopt-ad/ripopt"]
diff --git a/src/lib.rs b/src/lib.rs
@@ -1,7 +1,14 @@
-use feos_core::EosError;
+#[cfg(all(feature = "ipopt", feature = "ripopt"))]
+compile_error!("Features 'ipopt' and 'ripopt' cannot be enabled at the same time.");
+
+#[cfg(not(any(feature = "ipopt", feature = "ripopt")))]
+compile_error!("Either feature 'ipopt' or 'ripopt' must be enabled.");
+
+use feos::core::FeosError;
 use good_lp::{Constraint, Variable};
 use nalgebra::{SMatrix, SVector};
 use num_dual::DualNum;
+use quantity::MolarWeight;
 use std::array;
 use std::collections::{HashMap, HashSet};
 
@@ -13,18 +20,28 @@ pub use molecule::{CoMTCAMD, Disjunction, MolecularRepresentation, SuperMolecule
 pub use process::{ContinuousVariable, ProcessModel};
 pub use property::{GcPcSaftPropertyModel, PcSaftPropertyModel, PropertyModel};
 pub use solver::{
-    GeneralConstraint, MixedIntegerNonLinearProgram, OptimizationResult, OuterApproximation,
+    GeneralConstraint, MixedIntegerNonLinearProgram, OptimizationOptions, OptimizationResult,
+    OuterApproximation,
 };
 
 /// Input for group-contribution models that allows for derivatives.
 pub struct ChemicalRecord<D> {
     pub groups: HashMap<&'static str, D>,
     pub bonds: HashMap<[&'static str; 2], D>,
+    pub molar_weight: MolarWeight<D>,
 }
 
 impl<D> ChemicalRecord<D> {
-    pub fn new(groups: HashMap<&'static str, D>, bonds: HashMap<[&'static str; 2], D>) -> Self {
-        Self { groups, bonds }
+    pub fn new(
+        groups: HashMap<&'static str, D>,
+        bonds: HashMap<[&'static str; 2], D>,
+        molar_weight: MolarWeight<D>,
+    ) -> Self {
+        Self {
+            groups,
+            bonds,
+            molar_weight,
+        }
     }
 }
 
@@ -49,13 +66,13 @@ impl<M, R, P> IntegratedDesign<M, R, P> {
 impl<
         M: MolecularRepresentation<N_Y>,
         R: PropertyModel<N>,
-        P: ProcessModel<R::EquationOfState, N_X, N>,
+        P: ProcessModel<N_X, N>,
         const N_X: usize,
         const N_Y: usize,
         const N: usize,
     > MixedIntegerNonLinearProgram<N_X, N_Y, N> for IntegratedDesign<M, R, P>
 {
-    type Error = EosError;
+    type Error = FeosError;
 
     fn x_variables(&self) -> SVector<(f64, f64, f64), N_X> {
         SVector::from(self.process.variables().map(|v| (v.lobnd, v.upbnd, v.init)))
@@ -81,10 +98,10 @@ impl<
         &self,
         x: SVector<D, N_X>,
         y: SMatrix<D, N_Y, N>,
-    ) -> Result<(D, Vec<D>), EosError> {
+    ) -> Result<(D, Vec<D>), FeosError> {
         let y_set: HashSet<_> = y.data.0.iter().map(|y| y.map(|y| y.re() as i32)).collect();
         if y_set.len() != N {
-            Err(EosError::IncompatibleComponents(N, y_set.len()))
+            Err(FeosError::IncompatibleComponents(N, y_set.len()))
         } else {
             let cr = y.data.0.map(|y| self.molecule.build_molecule(y));
             let eos = self.property.build_eos(cr.each_ref());
@@ -170,11 +187,7 @@ mod test {
             result.x.data.0[0],
             MOLECULE.smiles(&result.y.data.0[0])
         );
-        assert_relative_eq!(
-            result.objective.0,
-            -0.4378352970105434,
-            max_relative = 1e-10
-        );
+        assert_relative_eq!(result.objective.0, -0.4378352970105434, max_relative = 1e-8);
     }
 
     #[test]
@@ -207,11 +220,7 @@ mod test {
             result.x.data.0[0],
             molecule.smiles(&result.y.data.0[0])
         );
-        assert_relative_eq!(
-            result.objective.0,
-            -0.4378352970105434,
-            max_relative = 1e-10
-        );
+        assert_relative_eq!(result.objective.0, -0.4378352970105434, max_relative = 1e-8);
     }
 
     #[test]

diff --git a/src/molecule/comt_camd.rs b/src/molecule/comt_camd.rs
@@ -2,51 +2,59 @@ use super::MolecularRepresentation;
 use crate::ChemicalRecord;
 use good_lp::{constraint, Constraint, Expression, Variable};
 use num_dual::DualNum;
+use quantity::MolarWeight;
 use std::collections::HashMap;
 use std::sync::LazyLock;
 
-struct Group {
-    name: &'static str,
+pub(super) struct Group {
+    pub name: &'static str,
     open_bonds: usize,
     n_max: i32,
-    heavy_atoms: usize,
+    heavy_atoms: i32,
+    pub molar_weight: f64,
 }
 
 impl Group {
-    const fn new(name: &'static str, open_bonds: usize, n_max: i32, heavy_atoms: usize) -> Self {
+    const fn new(name: &'static str, open_bonds: usize, n_max: i32, hcno: [i32; 4]) -> Self {
+        let [h, c, n, o] = hcno;
+        let heavy_atoms = c + n + o;
+        // values from PubChem https://pubchem.ncbi.nlm.nih.gov/ptable/atomic-mass/
+        let molar_weight =
+            h as f64 * 1.008 + c as f64 * 12.011 + n as f64 * 14.007 + o as f64 * 15.999;
         Self {
             name,
             open_bonds,
             n_max,
             heavy_atoms,
+            molar_weight,
         }
     }
 }
 
 const N_GROUPS: usize = 22;
-const GROUPS: [Group; N_GROUPS] = [
-    Group::new("CH3", 1, 10, 1),
-    Group::new("CH2", 2, 10, 1),
-    Group::new(">CH", 3, 10, 1),
-    Group::new(">C<", 4, 10, 1),
-    Group::new("=CH2", 1, 1, 1),
-    Group::new("=CH", 2, 2, 1),
-    Group::new("=C<", 3, 2, 1),
-    Group::new("C≡CH", 1, 1, 2),
-    Group::new("CH2_hex", 2, 6, 1),
-    Group::new("CH_hex", 3, 6, 1),
-    Group::new("CH2_pent", 2, 5, 1),
-    Group::new("CH_pent", 3, 5, 1),
-    Group::new("CH_arom", 2, 6, 1),
-    Group::new("C_arom", 3, 6, 1),
-    Group::new("CH=O", 1, 1, 2),
-    Group::new(">C=O", 2, 1, 2),
-    Group::new("OCH3", 1, 1, 2),
-    Group::new("OCH2", 2, 1, 2),
-    Group::new("HCOO", 1, 1, 3),
-    Group::new("COO", 2, 1, 3),
-    Group::new("OH", 1, 1, 1),
-    Group::new("NH2", 1, 1, 1),
+pub(super) const GROUPS: [Group; N_GROUPS] = [
+    Group::new("CH3", 1, 10, [3, 1, 0, 0]),
+    Group::new("CH2", 2, 10, [2, 1, 0, 0]),
+    Group::new(">CH", 3, 10, [1, 1, 0, 0]),
+    Group::new(">C<", 4, 10, [0, 1, 0, 0]),
+    Group::new("=CH2", 1, 1, [2, 1, 0, 0]),
+    Group::new("=CH", 2, 2, [1, 1, 0, 0]),
+    Group::new("=C<", 3, 2, [0, 1, 0, 0]),
+    Group::new("C≡CH", 1, 1, [1, 2, 0, 0]),
+    Group::new("CH2_hex", 2, 6, [2, 1, 0, 0]),
+    Group::new("CH_hex", 3, 6, [1, 1, 0, 0]),
+    Group::new("CH2_pent", 2, 5, [2, 1, 0, 0]),
+    Group::new("CH_pent", 3, 5, [1, 1, 0, 0]),
+    Group::new("CH_arom", 2, 6, [1, 1, 0, 0]),
+    Group::new("C_arom", 3, 6, [0, 1, 0, 0]),
+    Group::new("CH=O", 1, 1, [1, 1, 0, 1]),
+    Group::new(">C=O", 2, 1, [0, 1, 0, 1]),
+    Group::new("OCH3", 1, 1, [3, 1, 0, 1]),
+    Group::new("OCH2", 2, 1, [2, 1, 0, 1]),
+    Group::new("HCOO", 1, 1, [1, 1, 0, 2]),
+    Group::new("COO", 2, 1, [0, 1, 0, 2]),
+    Group::new("OH", 1, 1, [1, 0, 0, 1]),
+    Group::new("NH2", 1, 1, [2, 0, 1, 0]),
 ];
 
 struct Structure {
@@ -163,14 +171,19 @@ impl MolecularRepresentation<N_Y> for CoMTCAMD {
     ) -> ChemicalRecord<D> {
         let mut group_counts = [D::zero(); N_GROUPS];
         group_counts.copy_from_slice(&feature_variables[N_STRUCTURES..]);
+        let mut molar_weight = D::from(0.0);
         let groups: HashMap<_, _> = GROUPS
             .iter()
             .zip(group_counts)
-            .map(|(g, c)| (g.name, c))
+            .map(|(g, c)| {
+                molar_weight += c * g.molar_weight;
+                (g.name, c)
+            })
             .collect();
-        ChemicalRecord {
+        ChemicalRecord::new(
             groups,
-            bonds: HashMap::new(),
-        }
+            HashMap::new(),
+            MolarWeight::new(molar_weight * 1e-3),
+        )
     }
 }
diff --git a/src/molecule/disjunction.rs b/src/molecule/disjunction.rs
@@ -2,6 +2,7 @@ use super::{ChemicalRecord, MolecularRepresentation, SuperMolecule};
 use crate::GeneralConstraint;
 use good_lp::{constraint, Constraint, Expression, Variable};
 use num_dual::DualNum;
+use quantity::{Dimensionless, MolarWeight};
 use std::collections::HashMap;
 
 /// A combination of different molecule superstructures.
@@ -96,6 +97,7 @@ where
 
         let mut groups = HashMap::new();
         let mut bonds = HashMap::new();
+        let mut molar_weight = MolarWeight::new(D::from(0.0));
         for (m, c) in self.0.iter().zip(c) {
             let cr = m.build(y.to_vec());
             cr.groups
@@ -104,7 +106,8 @@ where
             cr.bonds
                 .into_iter()
                 .for_each(|(b, v)| *bonds.entry(b).or_insert(D::zero()) += v * c);
+            molar_weight += cr.molar_weight * Dimensionless::new(*c);
         }
-        ChemicalRecord { groups, bonds }
+        ChemicalRecord::new(groups, bonds, molar_weight)
     }
 }
diff --git a/src/molecule/polynomial.rs b/src/molecule/polynomial.rs
@@ -30,7 +30,7 @@ impl<D: DualNum<f64> + Copy, const N: usize> Polynomial<D, N> {
         self.0[0].into_iter().sum()
     }
 
-    pub fn iter(&self) -> Iter<D> {
+    pub fn iter(&self) -> Iter<'_, D> {
         self.0[0].iter()
     }
 }