diff --git a/src/chemistry.c b/src/chemistry.c
new file mode 100644
index 0000000000000000000000000000000000000000..4d2a5e7ba9565931ef371273baf1f6b7e3c5bc34
--- /dev/null
+++ b/src/chemistry.c
@@ -0,0 +1,54 @@
+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Copyright (c) 2016 Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+
+/* Config parameters. */
+#include "../config.h"
+
+/* This object's header. */
+#include "chemistry.h"
+
+/**
+ * @brief Initialises the chemistry properties.
+ *
+ * Calls chemistry_init_backend for the chosen chemistry function.
+ *
+ * @param parameter_file The parsed parameter file.
+ * @param us The current internal system of units.
+ * @param phys_const The physical constants in internal units.
+ * @param chemistry The chemistry properties to initialize
+ */
+void chemistry_init(const struct swift_params* parameter_file,
+ const struct unit_system* us,
+ const struct phys_const* phys_const,
+ struct chemistry_data* chemistry) {
+
+ chemistry_init_backend(parameter_file, us, phys_const, chemistry);
+}
+
+/**
+ * @brief Prints the properties of the chemistry model to stdout.
+ *
+ * Calls chemistry_print_backend for the chosen chemistry function.
+ *
+ * @param chemistry The properties of the chemistry function.
+ */
+void chemistry_print(const struct chemistry_data* chemistry) {
+
+ chemistry_print_backend(chemistry);
+}
diff --git a/src/chemistry.h b/src/chemistry.h
new file mode 100644
index 0000000000000000000000000000000000000000..25769240eb852e6b67a76ff3bc4e429305d09af6
--- /dev/null
+++ b/src/chemistry.h
@@ -0,0 +1,46 @@
+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Copyright (c) 2016 Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+#ifndef SWIFT_CHEMISTRY_H
+#define SWIFT_CHEMISTRY_H
+
+/**
+ * @file src/chemistry.h
+ * @brief Branches between the different chemistry functions.
+ */
+
+/* Config parameters. */
+#include "../config.h"
+#include "chemistry_struct.h"
+
+/* Import the right chemistry definition */
+#if defined(CHEMISTRY_NONE)
+#include "./chemistry/none/chemistry.h"
+#else
+#error "Invalid choice of chemistry function."
+#endif
+
+/* Common functions */
+void chemistry_init(const struct swift_params* parameter_file,
+ const struct unit_system* us,
+ const struct phys_const* phys_const,
+ struct chemistry_data* chem);
+
+void chemistry_print(const struct chemistry_data* chem);
+
+#endif /* SWIFT_CHEMISTRY_H */
diff --git a/src/chemistry/none/chemistry.h b/src/chemistry/none/chemistry.h
new file mode 100644
index 0000000000000000000000000000000000000000..6c17af00fd240d6d928168d0ab3a94882718bf17
--- /dev/null
+++ b/src/chemistry/none/chemistry.h
@@ -0,0 +1,77 @@
+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Copyright (c) 2016 Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+#ifndef SWIFT_CHEMISTRY_NONE_H
+#define SWIFT_CHEMISTRY_NONE_H
+
+/**
+ * @file src/chemistry/none/chemistry.h
+ * @brief Empty infrastructure for the cases without chemistry function
+ */
+
+/* Some standard headers. */
+#include <float.h>
+#include <math.h>
+
+/* Local includes. */
+#include "error.h"
+#include "hydro.h"
+#include "parser.h"
+#include "part.h"
+#include "physical_constants.h"
+#include "units.h"
+
+/**
+ * @brief Sets the chemistry properties of the (x-)particles to a valid start
+ * state.
+ *
+ * Nothing to do here.
+ *
+ * @param p Pointer to the particle data.
+ * @param xp Pointer to the extended particle data.
+ */
+__attribute__((always_inline)) INLINE static void chemistry_init_part(
+ const struct part* restrict p, struct xpart* restrict xp) {}
+
+/**
+ * @brief Initialises the chemistry properties.
+ *
+ * Nothing to do here.
+ *
+ * @param parameter_file The parsed parameter file.
+ * @param us The current internal system of units.
+ * @param phys_const The physical constants in internal units.
+ * @param chemistry The chemistry properties to initialize
+ */
+static INLINE void chemistry_init_backend(
+ const struct swift_params* parameter_file, const struct unit_system* us,
+ const struct phys_const* phys_const,
+ struct chemistry_data* chemistry) {}
+
+/**
+ * @brief Prints the properties of the chemistry model to stdout.
+ *
+ * @param chemistry The properties of the chemistry function.
+ */
+static INLINE void chemistry_print_backend(
+ const struct chemistry_data* chemistry) {
+
+ message("Chemistry function is 'No chemistry'.");
+}
+
+#endif /* SWIFT_CHEMISTRY_NONE_H */
diff --git a/src/chemistry/none/chemistry_io.h b/src/chemistry/none/chemistry_io.h
new file mode 100644
index 0000000000000000000000000000000000000000..979bd393855efa47ffcf236d668ddfe7136bf6f7
--- /dev/null
+++ b/src/chemistry/none/chemistry_io.h
@@ -0,0 +1,60 @@
+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Coypright (c) 2016 Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+
+#include "io_properties.h"
+
+/**
+ * @brief Specifies which particle fields to read from a dataset
+ *
+ * @param parts The particle array.
+ * @param list The list of i/o properties to read.
+ * @param num_fields The number of i/o fields to read.
+ */
+void chemistry_read_particles(struct part* parts, struct io_props* list,
+ int* num_fields) {
+
+ /* update num_fields and list according to hydro_io */
+}
+
+
+/**
+ * @brief Specifies which particle fields to write to a dataset
+ *
+ * @param parts The particle array.
+ * @param list The list of i/o properties to write.
+ * @param num_fields The number of i/o fields to write.
+ */
+void chemistry_write_particles(const struct part* parts, struct io_props* list,
+ int* num_fields) {
+
+ /* update num_fields and list according to hydro_io */
+}
+
+
+/**
+ * @brief Writes the current model of SPH to the file
+ * @param h_grpsph The HDF5 group in which to write
+ */
+void writeChemistryFlavor(hid_t h_grpsph) {
+
+ /* Viscosity and thermal conduction */
+ io_write_attribute_s(
+ h_grpsph, "Chemistry Model",
+ "None");
+}
diff --git a/src/chemistry/none/chemistry_struct.h b/src/chemistry/none/chemistry_struct.h
new file mode 100644
index 0000000000000000000000000000000000000000..01c39d9c1d321d0d68fcb5d499346c3202fc427e
--- /dev/null
+++ b/src/chemistry/none/chemistry_struct.h
@@ -0,0 +1,32 @@
+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Copyright (c) 2016 Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+#ifndef SWIFT_CHEMISTRY_STRUCT_NONE_H
+#define SWIFT_CHEMISTRY_STRUCT_NONE_H
+
+/**
+ * @file src/chemistry/none/chemistry_struct.h
+ * @brief Empty infrastructure for the cases without chemistry function
+ */
+
+/**
+ * @brief Properties of the chemistry function.
+ */
+struct chemistry_part_data {};
+
+#endif /* SWIFT_CHEMISTRY_STRUCT_NONE_H */
diff --git a/src/chemistry_io.h b/src/chemistry_io.h
new file mode 100644
index 0000000000000000000000000000000000000000..adcfb2b3ba53cbed4dd375b91fac484a49c4bfac
--- /dev/null
+++ b/src/chemistry_io.h
@@ -0,0 +1,32 @@
+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Coypright (c) 2016 Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+#ifndef SWIFT_CHEMISTRY_IO_H
+#define SWIFT_CHEMISTRY_IO_H
+
+/* Config parameters. */
+#include "../config.h"
+
+/* Import the right functions */
+#if defined(CHEMISTRY_NONE)
+#include "./chemistry/none/chemistry_io.h"
+#else
+#error "Invalid choice of chemistry function."
+#endif
+
+#endif /* SWIFT_CHEMISTRY_IO_H */
diff --git a/src/chemistry_struct.h b/src/chemistry_struct.h
new file mode 100644
index 0000000000000000000000000000000000000000..25998f8a4dc3d0a8441d67e713b4c74e71b96c48
--- /dev/null
+++ b/src/chemistry_struct.h
@@ -0,0 +1,37 @@
+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Copyright (c) 2016 Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+#ifndef SWIFT_CHEMISTRY_STRUCT_H
+#define SWIFT_CHEMISTRY_STRUCT_H
+
+/**
+ * @file src/chemistry_struct.h
+ * @brief Branches between the different chemistry functions.
+ */
+
+/* Config parameters. */
+#include "../config.h"
+
+/* Import the right chemistry definition */
+#if defined(CHEMISTRY_NONE)
+#include "./chemistry/none/chemistry_struct.h"
+#else
+#error "Invalid choice of chemistry function."
+#endif
+
+#endif /* SWIFT_CHEMISTRY_STRUCT_H */
diff --git a/src/cooling/grackle/cooling.h b/src/cooling/grackle/cooling.h
index f24105d70fbd681ea29e897bb74e43a09968ac28..94acc8641491f3d872384df7611ad3722e26900b 100644
--- a/src/cooling/grackle/cooling.h
+++ b/src/cooling/grackle/cooling.h
@@ -32,6 +32,7 @@
/* Local includes. */
#include "error.h"
#include "hydro.h"
+#include "io_properties.h"
#include "parser.h"
#include "part.h"
#include "physical_constants.h"
@@ -41,6 +42,18 @@
#define GRACKLE_NPART 1
#define GRACKLE_RANK 3
+/**
+ * @brief Writes the current model of SPH to the file
+ * @param h_grpsph The HDF5 group in which to write
+ */
+void writeCoolingFlavor(hid_t h_grpsph) {
+
+ /* Viscosity and thermal conduction */
+ io_write_attribute_s(
+ h_grpsph, "Chemistry Model",
+ "Grackle");
+}
+
/**
* @brief Sets the cooling properties of the (x-)particles to a valid start
* state.
diff --git a/src/cooling/grackle/cooling_io.h b/src/cooling/grackle/cooling_io.h
index 4f6e02f9b9220c51510418b969ac4315a925604d..2b9859d39ccb248bc790f7c6c9fadff508b83d3f 100644
--- a/src/cooling/grackle/cooling_io.h
+++ b/src/cooling/grackle/cooling_io.h
@@ -19,46 +19,6 @@
#include "io_properties.h"
-/**
- * @brief Specifies which particle fields to read from a dataset
- *
- * @param parts The particle array.
- * @param list The list of i/o properties to read.
- * @param num_fields The number of i/o fields to read.
- */
-void cooling_read_particles(struct part* parts, struct io_props* list,
- int* num_fields) {
-
- list += *num_fields;
- *num_fields += 1;
-
- /* List what we want to read */
- list[0] = io_make_input_field("HeDensity", FLOAT, 1, COMPULSORY,
- UNIT_CONV_DENSITY, parts, cooling_data.He_density);
-
-}
-
-
-/**
- * @brief Specifies which particle fields to write to a dataset
- *
- * @param parts The particle array.
- * @param list The list of i/o properties to write.
- * @param num_fields The number of i/o fields to write.
- */
-void cooling_write_particles(const struct part* parts, struct io_props* list,
- int* num_fields) {
-
- int i = *num_fields;
- /* List what we want to write */
- list[i] = io_make_output_field(
- "HeDensity", FLOAT, 1, UNIT_CONV_DENSITY, parts, cooling_data.He_density);
- i++;
-
- *num_fields = i;
-}
-
-
/**
* @brief Writes the current model of SPH to the file
* @param h_grpsph The HDF5 group in which to write
diff --git a/src/cooling/grackle/cooling_struct.h b/src/cooling/grackle/cooling_struct.h
index ec1bd6cb8f4f9025e25f1b59c78183921761f9ff..8895137eb9884c54fd982ee9a2b1d61db453a44d 100644
--- a/src/cooling/grackle/cooling_struct.h
+++ b/src/cooling/grackle/cooling_struct.h
@@ -62,13 +62,4 @@ struct cooling_xpart_data {
float radiated_energy;
};
-/**
- * @brief Properties of the cooling stored in the particle data
- */
-struct cooling_part_data {
-
- /*! Quick example */
- float He_density;
-};
-
#endif /* SWIFT_COOLING_STRUCT_NONE_H */
diff --git a/src/hydro/Gadget2/hydro_part.h b/src/hydro/Gadget2/hydro_part.h
index 4bfdbcf7ff9f25d1448c8e44cf914f6b8a9da9e6..98ad9c86be620454a92a5bb01e1127385b561642 100644
--- a/src/hydro/Gadget2/hydro_part.h
+++ b/src/hydro/Gadget2/hydro_part.h
@@ -31,7 +31,7 @@
* Gadget-2 tree-code neighbours search.
*/
-#include "cooling_struct.h"
+#include "chemistry_struct.h"
/* Extra particle data not needed during the SPH loops over neighbours. */
struct xpart {
@@ -133,7 +133,7 @@ struct part {
/* Time-step length */
timebin_t time_bin;
- struct cooling_part_data cooling_data;
+ struct chemistry_part_data chemistry_data;
#ifdef SWIFT_DEBUG_CHECKS