account for the particle mass in the RE MC move

src/core/reaction_ensemble.cpp

@@ -832,10 +832,10 @@ bool ReactionAlgorithm::do_global_mc_move_for_particles_of_type(
     // change particle position
     new_pos = get_random_position_in_box();
     double vel[3];
-    // we use mass=1 for all particles, think about adapting this
-    vel[0] = std::sqrt(temperature) * gaussian_random();
-    vel[1] = std::sqrt(temperature) * gaussian_random();
-    vel[2] = std::sqrt(temperature) * gaussian_random();
+    auto const &p = get_particle_data(p_id);
+    vel[0] = std::sqrt(temperature / p.p.mass) * gaussian_random();
+    vel[1] = std::sqrt(temperature / p.p.mass) * gaussian_random();
+    vel[2] = std::sqrt(temperature / p.p.mass) * gaussian_random();
     set_particle_v(p_id, vel);
     // new_pos=get_random_position_in_box_enhanced_proposal_of_small_radii();
     // //enhanced proposal of small radii

src/python/espressomd/reaction_ensemble.pyx

@@ -16,8 +16,9 @@ cdef class ReactionAlgorithm(object):
     reaction algorithm by setting the standard pressure, temperature, and the
     exclusion radius.
 
-    Note: When setting the velocities of the particles according the the
-    Maxwell distribution the mass of all particles is assumed to equal 1.
+    Note: When creating particles the velocities the new particles are set
+    according the Maxwell distribution. In this step the mass of the new particle
+    is assumed to equal 1.
 
 
     Parameters