Docs updated

doc/src/pair_coul_tt.rst

@@ -40,35 +40,34 @@ The *coul/tt* pair style should be used as a sub-style within in the
 :doc:`pair_style hybrid/overlay <pair_hybrid>` command, in conjunction with a
 main pair style including Coulomb interactions and *thole* pair style, 
 or with *lj/cut/thole/long* pair style that is equivalent to the combination 
-of two preceding.
+of preceding two.
 
 The *coul/tt* pair styles compute the charge-dipole Coulomb interaction damped 
 at short distances by a function
 
 .. math::
 
-  TT_{ij}(r) = 1 - c_{ij} \cdot e^{-b_{ij} r} \sum_{k=0}^n \frac{(b_{ij} r)^k}{k!}
+  f_{n,ij}(r) = 1 - c_{ij} \cdot e^{-b_{ij} r} \sum_{k=0}^n \frac{(b_{ij} r)^k}{k!}
 
-This function results from an adaptation to Coulomb interaction :ref:`(Salanne) 
-<Salanne1>` the damping function originally proposed
-by :ref:`(Tang Toennies) <TangToennies1>` for van der Waals interactions.
+This function results from an adaptation to the Coulomb interaction :ref:`(Salanne) 
+<Salanne1>` of the damping function originally proposed
+by :ref:`Tang Toennies <TangToennies1>` for van der Waals interactions.
 
-The polynomial takes the degree of 4 for damping Coulomb interaction.
+The polynomial takes the degree 4 for damping the Coulomb interaction.
 The parameters :math:`b_{ij}` and :math:`c_{ij}` could be determined from 
 first-principle calculations for small, mainly mono-atomic, ions :ref:`(Salanne) 
-<Salanne1>` or chosen as empirical for large molecules.
+<Salanne1>`, or else treated as empirical for large molecules.
 
-The damping function is typically applied to the interactions between a Drude 
-charge (:math:`q_{D,i}` on a Drude particle or :math:`-q_{D,i}` on the respective 
-Drude core particle bonded to a Drude particle) and a charge of a non-polarizable 
-atom, :math:`q_{j}`. The Tang-Toennies function could be used to damp electrostatic 
-interaction between two Drude cores acting on the partial charge of the one core 
-:math:`q_{i}-q_{D,i}` and a Drude charge of the another one :math:`-q_{D,j}`, and 
-the opposite case, respectively. The :math:`b_{ij}` and :math:`c_{ij}` are equal 
-to :math:`b_{ji}` and :math:`c_{ji}` in case of core - core interaction.
-Therefore, the screening is not applied to the full charge of the Drude core 
-:math:`q_i`, but only to the :math:`-q_{D,i}` part of it when it acts as a 
-dipole or :math:`q_{i}-q_{D,i}` when it acts as a charge. 
+In pair styles with Drude induced dipoles, this damping function is typically 
+applied to the interactions between a Drude charge (either :math:`q_{D,i}` on 
+a Drude particle or :math:`-q_{D,i}` on the respective 
+Drude core)) and a charge on a non-polarizable atom, :math:`q_{j}`. 
+
+The Tang-Toennies function could also be used to damp electrostatic 
+interactions between the (non-polarizable part of the) charge of a core, 
+:math:`q_{i}-q_{D,i}`, and the Drude charge of another, :math:`-q_{D,j}`. 
+The :math:`b_{ij}` and :math:`c_{ij}` are equal  to :math:`b_{ji}` and 
+:math:`c_{ji}` in the case of core-core interactions.
 
 For pair_style *coul/tt*\ , the following coefficients must be defined for
 each pair of atoms types via the :doc:`pair_coeff <pair_coeff>` command
@@ -80,9 +79,9 @@ as in the example above.
 * cutoff (distance units)
 
 The last two coefficients are optional.  If not specified the global 
-degree of polynomial or global cutoff specified in the pair_style
-command are used. In order to specify a cutoff (forth argument) a damp
-parameter (third argument) must also be specified.
+degree of the polynomial or the global cutoff specified in the pair_style
+command are used. In order to specify a cutoff (forth argument), the degree of 
+the polynomial (third argument) must also be specified.
 
 ----------
 

src/USER-DRUDE/README

@@ -7,7 +7,7 @@ features:
 using Langevin or Nosé-Hoover thermostats
 * computation of the atom and dipole temperatures
 * damping induced dipole interactions using Thole's function
-* charge-dipole damping using Tang-Toennies damping function
+* charge-dipole damping using Tang-Toennies function
 
 See the file doc/drude_tutorial.html for getting started.