Documentation update

git-svn-id: http://qeforge.qe-forge.org/svn/q-e/trunk/espresso@2700 c92efa57-630b-4861-b058-cf58834340f0

Doc/refman.tex

@@ -463,6 +463,21 @@ that you have locally modified; conflicting files will contain lines like
 \end{verbatim}
 If this happen, you must edit the file manually to remove conflicts.
 
+You can compare your local copy with any version of the repository
+using 
+\begin{verbatim}
+  cvs diff -r tag
+\end{verbatim}
+or with the repository at a given date using 
+\begin{verbatim}
+  cvs diff -D date
+\end{verbatim}
+You can also compare two different versions/snapshots of the repository, 
+by specifying two different tags or dates. Options \texttt{-i} (ignore case),  
+\texttt{-w} (ignore all white spaces), \texttt{-b} (ignore changes in 
+the number of white spaces) may be useful to distinguish true changes
+from ``esthetic'' changes such as indentation.
+
 READ-WRITE ACCESS ONLY:
 
 In order to save your changes to the repository, use

Doc/users-guide.tex

@@ -1182,9 +1182,19 @@ Update to the last version (presently 7.1.41, 8.0.046 or
 {\texttt{http://developer.intel.com/software/products/support/\#premier}}%
 {http://developer.intel.com/software/products/support/\#premier}.
 \hfill\break
-Intel v.~9 should work, but earlier releases had a bug in preprocessing
-that prevents compilation of {\tt iotk}. Use the last available version
-with the most patches.
+Intel v.~9 has a buggy preprocessing that either prevents compilation 
+of \texttt{iotk}, or produces runtime errors in \texttt{cft3}. Workaround:
+modify \texttt{make.sys} to explicitly perform preprocessing using
+\texttt{/lib/cpp}, as in the following example (courtesy from Sergei
+Lysenkov):
+\begin{verbatim}
+.f90.o:
+        $(CPP) $(CPPFLAGS) $< -o $*.F90
+        $(MPIF90) $(F90FLAGS) -c $*.F90 -o $*.o
+
+CPP            = /lib/cpp
+CPPFLAGS       = -P -C -traditional $(DFLAGS) $(IFLAGS)
+\end{verbatim}
 
 Warnings ``size of symbol ... changed ...'' are produced by ifc 7.1 at
 the loading stage.
@@ -3041,4 +3051,24 @@ group of \textbf{q}, the code compares \textbf{q} and the rotated
 You may run into trouble if your \textbf{q}-point differs from a
 high-symmetry point by an amount in that order of magnitude.
 
+\section{Frequently Asked Questions}
+
+\begin{itemize}
+\item {\em How can I optimize the structural parameters of a
+low-symmetry lattice? should I use $E(v)$ curves, the stress,
+variable-cell molecular dynamics?}
+
+  \item {\em Is there a simple way to determine the symmetry
+of a given phonon mode?}
+
+In some cases, degeneracy will help. In other cases, the character of a
+mode can be easily determined by direct inspection. In general, one needs
+to perform a group-symmetry analysis of the phonon mode, and this is 
+presently not implemented. So the short answer is: no, only not-so-simple 
+ways.
+
+You might find the ISOTROPY package useful:\\
+\htmladdnormallink{\texttt{http://stokes.byu.edu/iso/isotropy.html}}%
+                          {http://stokes.byu.edu/iso/isotropy.html}.
+\end{itemize}
 \end{document}