Rewrite LJcos2 interaction interface

src/core/nonbonded_interactions/ljcos2.cpp

@@ -25,33 +25,24 @@
 #include "ljcos2.hpp"
 
 #ifdef LJCOS2
-#include "interactions.hpp"
 #include "nonbonded_interaction_data.hpp"
 
-#include <utils/constants.hpp>
-
 #include <cmath>
-
-int ljcos2_set_params(int part_type_a, int part_type_b, double eps, double sig,
-                      double offset, double w) {
-  IA_parameters *data = get_ia_param_safe(part_type_a, part_type_b);
-
-  if (!data)
-    return ES_ERROR;
-
-  data->ljcos2.eps = eps;
-  data->ljcos2.sig = sig;
-  data->ljcos2.offset = offset;
-  data->ljcos2.w = w;
-
-  /* calculate dependent parameters */
-  data->ljcos2.rchange = pow(2, 1 / 6.) * sig;
-  data->ljcos2.cut = w + data->ljcos2.rchange;
-
-  /* broadcast interaction parameters */
-  mpi_bcast_ia_params(part_type_a, part_type_b);
-
-  return ES_OK;
+#include <stdexcept>
+
+LJcos2_Parameters::LJcos2_Parameters(double eps, double sig, double offset,
+                                     double w)
+    : eps{eps}, sig{sig}, offset{offset}, w{w} {
+  if (eps < 0.) {
+    throw std::domain_error("LJcos2 parameter 'epsilon' has to be >= 0");
+  }
+  if (sig < 0.) {
+    throw std::domain_error("LJcos2 parameter 'sigma' has to be >= 0");
+  }
+  if (sig != 0.) {
+    rchange = std::pow(2., 1. / 6.) * sig;
+    cut = w + rchange;
+  }
 }
 
 #endif /* ifdef LJCOS2 */

src/core/nonbonded_interactions/ljcos2.hpp

@@ -36,16 +36,12 @@
 
 #include "nonbonded_interaction_data.hpp"
 
-#include <utils/Vector.hpp>
 #include <utils/constants.hpp>
 #include <utils/math/int_pow.hpp>
 #include <utils/math/sqr.hpp>
 
 #include <cmath>
 
-int ljcos2_set_params(int part_type_a, int part_type_b, double eps, double sig,
-                      double offset, double w);
-
 /** Calculate Lennard-Jones cosine squared force factor */
 inline double ljcos2_pair_force_factor(IA_parameters const &ia_params,
                                        double dist) {

src/core/nonbonded_interactions/nonbonded_interaction_data.cpp

@@ -192,8 +192,7 @@ static double recalc_maximal_cutoff(const IA_parameters &data) {
 #endif
 
 #ifdef LJCOS2
-  max_cut_current =
-      std::max(max_cut_current, (data.ljcos2.cut + data.ljcos2.offset));
+  max_cut_current = std::max(max_cut_current, data.ljcos2.max_cutoff());
 #endif
 
 #ifdef GAY_BERNE

src/core/nonbonded_interactions/nonbonded_interaction_data.hpp

@@ -172,6 +172,9 @@ struct LJcos2_Parameters {
   double offset = 0.0;
   double w = 0.0;
   double rchange = 0.0;
+  LJcos2_Parameters() = default;
+  LJcos2_Parameters(double eps, double sig, double offset, double w);
+  double max_cutoff() const { return cut + offset; }
 };
 
 /** Gay-Berne potential */

src/python/espressomd/interactions.pxd

@@ -106,12 +106,6 @@ cdef extern from "nonbonded_interactions/nonbonded_interaction_data.hpp":
         double Fmax
         double r
 
-    cdef struct LJcos2_Parameters:
-        double eps
-        double sig
-        double offset
-        double w
-
     cdef struct GayBerne_Parameters:
         double eps
         double sig
@@ -134,8 +128,6 @@ cdef extern from "nonbonded_interactions/nonbonded_interaction_data.hpp":
 
     cdef struct IA_parameters:
 
-        LJcos2_Parameters ljcos2
-
         LJGen_Parameters ljgen
 
         SoftSphere_Parameters soft_sphere
@@ -168,12 +160,6 @@ cdef extern from "nonbonded_interactions/nonbonded_interaction_data.hpp":
     cdef void ia_params_set_state(string)
     cdef void reset_ia_params()
 
-IF LJCOS2:
-    cdef extern from "nonbonded_interactions/ljcos2.hpp":
-        cdef int ljcos2_set_params(int part_type_a, int part_type_b,
-                                   double eps, double sig, double offset,
-                                   double w)
-
 IF GAY_BERNE:
     cdef extern from "nonbonded_interactions/gay_berne.hpp":
         int gay_berne_set_params(int part_type_a, int part_type_b,

src/python/espressomd/interactions.pyx

@@ -618,38 +618,22 @@ IF LJCOS == 1:
             """
             return {"epsilon", "sigma", "cutoff"}
 
-IF LJCOS2:
+IF LJCOS2 == 1:
 
-    cdef class LennardJonesCos2Interaction(NonBondedInteraction):
-
-        def validate_params(self):
-            if self._params["epsilon"] < 0:
-                raise ValueError("Lennard-Jones epsilon has to be >=0")
-            if self._params["sigma"] < 0:
-                raise ValueError("Lennard-Jones sigma has to be >=0")
-            if self._params["width"] < 0:
-                raise ValueError("Parameter width has to be >=0")
-
-        def _get_params_from_es_core(self):
-            cdef IA_parameters * ia_params
-            ia_params = get_ia_param_safe(
-                self._part_types[0],
-                self._part_types[1])
-            return{
-                "epsilon": ia_params.ljcos2.eps,
-                "sigma": ia_params.ljcos2.sig,
-                "offset": ia_params.ljcos2.offset,
-                "width": ia_params.ljcos2.w}
-
-        def is_active(self):
-            return (self._params["epsilon"] > 0)
+    @script_interface_register
+    class LennardJonesCos2Interaction(NewNonBondedInteraction):
+        """Second variant of the Lennard-Jones cosine interaction.
 
-        def set_params(self, **kwargs):
-            """Set parameters for the Lennard-Jones cosine squared interaction.
+        Methods
+        -------
+        set_params()
+            Set or update parameters for the interaction.
+            Parameters marked as required become optional once the
+            interaction has been activated for the first time;
+            subsequent calls to this method update the existing values.
 
             Parameters
             ----------
-
             epsilon : :obj:`float`
                 Magnitude of the interaction.
             sigma : :obj:`float`
@@ -658,18 +642,12 @@ IF LJCOS2:
                 Offset distance of the interaction.
             width : :obj:`float`
                 Width of interaction.
-            """
-            super().set_params(**kwargs)
+        """
 
-        def _set_params_in_es_core(self):
-            if ljcos2_set_params(self._part_types[0],
-                                 self._part_types[1],
-                                 self._params["epsilon"],
-                                 self._params["sigma"],
-                                 self._params["offset"],
-                                 self._params["width"]):
-                raise Exception(
-                    "Could not set Lennard-Jones Cosine2 parameters")
+        _so_name = "Interactions::InteractionLJcos2"
+
+        def is_active(self):
+            return self.epsilon > 0.
 
         def default_params(self):
             return {"offset": 0.}
@@ -684,14 +662,18 @@ IF LJCOS2:
             """All parameters that can be set.
 
             """
-            return {"epsilon", "sigma", "offset", "width"}
+            return {"epsilon", "sigma", "width", "offset"}
 
         def required_keys(self):
             """Parameters that have to be set.
 
             """
             return {"epsilon", "sigma", "width"}
 
+        @property
+        def cutoff(self):
+            return self.call_method("get_cutoff")
+
 IF HAT == 1:
 
     cdef class HatInteraction(NonBondedInteraction):
@@ -1564,9 +1546,6 @@ class NonBondedInteractionHandle(ScriptInterfaceHelper):
         IF LENNARD_JONES_GENERIC:
             self.generic_lennard_jones = GenericLennardJonesInteraction(
                 _type1, _type2)
-        IF LJCOS2:
-            self.lennard_jones_cos2 = LennardJonesCos2Interaction(
-                _type1, _type2)
         IF SMOOTH_STEP:
             self.smooth_step = SmoothStepInteraction(_type1, _type2)
         IF BMHTF_NACL:

src/script_interface/interactions/NonBondedInteraction.hpp

@@ -222,6 +222,41 @@ class InteractionLJcos
 };
 #endif // LJCOS
 
+#ifdef LJCOS2
+class InteractionLJcos2
+    : public InteractionPotentialInterface<::LJcos2_Parameters> {
+protected:
+  CoreInteraction IA_parameters::*get_ptr_offset() const override {
+    return &::IA_parameters::ljcos2;
+  }
+
+public:
+  InteractionLJcos2() {
+    add_parameters({
+        make_autoparameter(&CoreInteraction::eps, "epsilon"),
+        make_autoparameter(&CoreInteraction::sig, "sigma"),
+        make_autoparameter(&CoreInteraction::offset, "offset"),
+        make_autoparameter(&CoreInteraction::w, "width"),
+    });
+  }
+
+  void make_new_instance(VariantMap const &params) override {
+    m_ia_si =
+        make_shared_from_args<CoreInteraction, double, double, double, double>(
+            params, "epsilon", "sigma", "offset", "width");
+  }
+
+  Variant do_call_method(std::string const &name,
+                         VariantMap const &params) override {
+    if (name == "get_cutoff") {
+      return m_ia_si.get()->cut;
+    }
+    return InteractionPotentialInterface<CoreInteraction>::do_call_method(
+        name, params);
+  }
+};
+#endif // LJCOS2
+
 class NonBondedInteractionHandle
     : public AutoParameters<NonBondedInteractionHandle> {
   std::array<int, 2> m_types = {-1, -1};
@@ -235,6 +270,9 @@ class NonBondedInteractionHandle
 #ifdef LJCOS
   std::shared_ptr<InteractionLJcos> m_ljcos;
 #endif
+#ifdef LJCOS2
+  std::shared_ptr<InteractionLJcos2> m_ljcos2;
+#endif
 
   template <class T>
   auto make_autoparameter(std::shared_ptr<T> &member, const char *key) const {
@@ -261,6 +299,9 @@ class NonBondedInteractionHandle
 #endif
 #ifdef LJCOS
         make_autoparameter(m_ljcos, "lennard_jones_cos"),
+#endif
+#ifdef LJCOS2
+        make_autoparameter(m_ljcos2, "lennard_jones_cos2"),
 #endif
     });
   }
@@ -311,6 +352,10 @@ class NonBondedInteractionHandle
 #ifdef LJCOS
     set_member<InteractionLJcos>(m_ljcos, "lennard_jones_cos",
                                  "Interactions::InteractionLJcos", params);
+#endif
+#ifdef LJCOS2
+    set_member<InteractionLJcos2>(m_ljcos2, "lennard_jones_cos2",
+                                  "Interactions::InteractionLJcos2", params);
 #endif
   }
 

src/script_interface/interactions/initialize.cpp

@@ -62,6 +62,9 @@ void initialize(Utils::Factory<ObjectHandle> *om) {
 #ifdef LJCOS
   om->register_new<InteractionLJcos>("Interactions::InteractionLJcos");
 #endif
+#ifdef LJCOS2
+  om->register_new<InteractionLJcos2>("Interactions::InteractionLJcos2");
+#endif
 #ifdef WCA
   om->register_new<InteractionWCA>("Interactions::InteractionWCA");
 #endif

testsuite/python/interactions_non-bonded_interface.py

@@ -254,6 +254,13 @@ def test_lj_cos_exceptions(self):
             {"epsilon": 1., "sigma": 1., "cutoff": 1.5, "offset": 0.2},
             ("epsilon", "sigma"))
 
+    @utx.skipIfMissingFeatures("LJCOS2")
+    def test_lj_cos2_exceptions(self):
+        self.check_potential_exceptions(
+            espressomd.interactions.LennardJonesCos2Interaction,
+            {"epsilon": 1., "sigma": 1., "width": 1.5, "offset": 0.2},
+            ("epsilon", "sigma"))
+
 
 if __name__ == "__main__":
     ut.main()