Minor update of document

doc/phonopy/citation.rst

@@ -6,22 +6,39 @@ Citation of phonopy
 
 If you have used phonopy, please cite the following article:
 
-- "First-principles calculations of the ferroelastic transition
-  between rutile-type and CaCl2-type SiO2 at high pressures",
-  Atsushi Togo, Fumiyasu Oba, and Isao Tanaka, Phys. Rev. B, 78, 134106 (2008)
+"First principles phonon calculations in materials science",
+Atsushi Togo and Isao Tanaka, Scr. Mater., 108, 1-5 (2015)
 
 ::
 
-  @article {phonopy,
-       Journal = {Phys. rev. B},
-       Year = {2008},
-       Title = {First-principles calculations of the ferroelastic transition between rutile-type and CaCl2-type SiO2 at high pressures},
-       Author = {Togo, A and Oba, F and Tanaka, I},
-       Pages = {134106},
-       Volume = {78},
-       Issue = {13},
-       Month = {Oct}
-  }
+   @article {phonopy,
+        Journal = {Scr. Mater.},
+        Year = {2015},
+        Title = {First principles phonon calculations in materials science},
+        Author = {Togo, A and Tanaka, I},
+        Pages = {1--5},
+        Volume = {108},
+        Month = {Nov}
+   }
+
+
+..
+   - "First-principles calculations of the ferroelastic transition
+     between rutile-type and CaCl2-type SiO2 at high pressures",
+     Atsushi Togo, Fumiyasu Oba, and Isao Tanaka, Phys. Rev. B, 78, 134106 (2008)
+
+   ::
+
+      @article {phonopy,
+	   Journal = {Phys. rev. B},
+	   Year = {2008},
+	   Title = {First-principles calculations of the ferroelastic transition between rutile-type and CaCl2-type SiO2 at high pressures},
+	   Author = {Togo, A and Oba, F and Tanaka, I},
+	   Pages = {134106},
+	   Volume = {78},
+	   Issue = {13},
+	   Month = {Oct}
+      }
 
 Some papers where phonopy was used
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