docs(docs): added extensive docs

src/network/include/gridfire/screening/screening_abstract.h

@@ -9,11 +9,67 @@
 #include <vector>
 
 namespace gridfire::screening {
+    /**
+     * @class ScreeningModel
+     * @brief An abstract base class for plasma screening models.
+     *
+     * This class defines the interface for models that calculate the enhancement
+     * factor for nuclear reaction rates due to the electrostatic screening of
+     * interacting nuclei by the surrounding plasma. Concrete implementations of
+     * this class will provide specific screening prescriptions (e.g., WEAK,
+     * BARE, STRONG, etc.).
+     *
+     * The interface provides methods for calculating screening factors for both
+     * standard double-precision inputs and for CppAD's automatic differentiation
+     * types, allowing the screening contributions to be included in Jacobian
+     * calculations.
+     */
     class ScreeningModel {
     public:
+        /// @brief Alias for CppAD Automatic Differentiation type for double precision.
         using ADDouble = CppAD::AD<double>;
+        /**
+         * @brief Virtual destructor.
+         *
+         * Ensures that derived class destructors are called correctly.
+         */
         virtual ~ScreeningModel() = default;
 
+        /**
+         * @brief Calculates screening factors for a set of reactions.
+         *
+         * This is a pure virtual function that must be implemented by derived
+         * classes. It computes the screening enhancement factor for each reaction
+         * in the provided set based on the given plasma conditions.
+         *
+         * @param reactions The set of logical reactions in the network.
+         * @param species A vector of all atomic species involved in the network.
+         * @param Y A vector of the molar abundances (mol/g) for each species.
+         * @param T9 The temperature in units of 10^9 K.
+         * @param rho The plasma density in g/cm^3.
+         * @return A vector of screening factors (dimensionless), one for each reaction
+         *         in the `reactions` set, in the same order.
+         *
+         * @b Pre-conditions
+         * - The size of the `Y` vector must match the size of the `species` vector.
+         * - `T9` and `rho` must be positive.
+         *
+         * @b Post-conditions
+         * - The returned vector will have the same size as the `reactions` set.
+         * - Each element in the returned vector will be >= 1.0.
+         *
+         * @b Usage
+         * @code
+         * // Assume 'model' is a std::unique_ptr<ScreeningModel> to a concrete implementation
+         * // and other parameters (reactions, species, Y, T9, rho) are initialized.
+         * std::vector<double> screening_factors = model->calculateScreeningFactors(
+         *     reactions, species, Y, T9, rho
+         * );
+         * for (size_t i = 0; i < reactions.size(); ++i) {
+         *     // ... use screening_factors[i] ...
+         * }
+         * @endcode
+         */
         virtual std::vector<double> calculateScreeningFactors(
             const reaction::LogicalReactionSet& reactions,
             const std::vector<fourdst::atomic::Species>& species,
@@ -22,6 +78,25 @@ namespace gridfire::screening {
             const double rho
             ) const = 0;
 
+        /**
+         * @brief Calculates screening factors using CppAD types for automatic differentiation.
+         *
+         * This is a pure virtual function that provides an overload of
+         * `calculateScreeningFactors` for use with CppAD. It allows the derivatives
+         * of the screening factors with respect to abundances, temperature, and
+         * density to be computed automatically.
+         *
+         * @param reactions The set of logical reactions in the network.
+         * @param species A vector of all atomic species involved in the network.
+         * @param Y A vector of the molar abundances (mol/g) for each species, as AD types.
+         * @param T9 The temperature in units of 10^9 K, as an AD type.
+         * @param rho The plasma density in g/cm^3, as an AD type.
+         * @return A vector of screening factors (dimensionless), as AD types.
+         *
+         * @b Note
+         * This method is essential for including the effects of screening in the
+         * Jacobian matrix of the reaction network.
+         */
         virtual std::vector<ADDouble> calculateScreeningFactors(
             const reaction::LogicalReactionSet& reactions,
             const std::vector<fourdst::atomic::Species>& species,