Edit the documentation.

docs/source/formalism/formalism_anphon.rst

@@ -268,6 +268,7 @@ where :math:`g_{2}` is a dimensionless factor given by
 Here, :math:`f_{i}` is the fraction of :math:`i`\ th isotope of an element having mass :math:`m_i`, 
 and :math:`M_{\kappa}=\sum_{i}f_{i}m_{i}(\kappa)` is the average mass, respectively.
 The :math:`g_{2}` values should be provided by the ``ISOFACT``-tag.
+The average mass :math:`M_{\kappa}` is substituted by the value specified in the ``MASS``-tag.
 
 Lattice thermal conductivity
 ----------------------------

docs/source/input/inputanphon.rst

@@ -401,14 +401,16 @@ The first entry **KPMODE** specifies the types of calculation which is followed
 
 * ISOTOPE-tag = 0 | 1
 
- === ===================================================================
+ === =========================================================================
   0   Do not consider phonon-isotope scatterings
   1   Consider phonon-isotope scatterings
- === ===================================================================
+  2   Consider phonon-isotope scatterings as in ``ISOTOPE = 1`` and 
+      the corresponding selfenergy will be stored in ``PREFIX``.gamma_isotope
+ === =========================================================================
 
  :Default: 0
  :Type: Integer
- :Description: When ``MODE = RTA`` and ``ISOTOPE = 1``, phonon scatterings due to isotopes will be considered perturbatively. ``ISOFACT`` should be properly given.
+ :Description: When ``MODE = RTA`` and ``ISOTOPE = 1 or 2``, phonon scatterings due to isotopes will be considered perturbatively. ``ISOFACT`` should be properly given.
 
 ````
 

docs/source/output.rst

@@ -117,3 +117,9 @@ Output files of anphon
 
  Lattice thermal conductivity tensor.
  Created when ``MODE = RTA``.
+
+* ``PREFIX``.gamma_isotope
+
+Phonon selfenergy due to isotope scatterings calculated by the Tamura's formula.
+Created when ``MODE = RTA`` and ``ISOTOPE = 2``.
+