added note on Intel MPI

user-doc/Installation.txt

@@ -670,6 +670,15 @@ ld: TOC section size exceeds 64k
 \verbatim
 export CRAYPE_LINK_TYPE=dynamic
 \endverbatim
+- Intel MPI seems to require the flags `-lmpi_mt -mt_mpi` for compiling and linking and the flag `-DMPICH_IGNORE_CXX_SEEK` for compiling
+  (kindly reported by Abhishek Acharya).
+  You might want to try to configure using
+\verbatim
+./configure LDFLAGS=-lmpi_mt CXXFLAGS="-DMPICH_IGNORE_CXX_SEEK -mt_mpi" STATIC_LIBS=-mt_mpi
+\endverbatim
+  Adding libraries to `STATIC_LIBS` uses them for all the linking steps, whereas those in `LIBS` are only used when linking the PLUMED kernel library.
+  See more at [this thread](https://groups.google.com/d/msgid/plumed-users/CAB1aw3y0m%3D5qwzsZY4ZB-aBevsL5iuS%3DmQuSWK_cw527zCMqzg%40mail.gmail.com?utm_medium=email&utm_source=footer).
+\endverbatim
 
 \page CodeSpecificNotes Code specific notes