=========
                       WANNIER90
                       =========                            
                                                            
 The Maximally-Localised Generalised Wannier Functions Code 



 INSTALLATION
 ------------

 Requirements: A Fortran 95 compiler (most f90 compilers are really f95)
               LAPACK and BLAS libraries

 Configuration:
   The system dependant parameters (eg compiler name) are contained in a file
   called 'make.sys'. Sample files may be found in the ./config/ directory.
   Choose one that is nearest to your setup and copy it to make.sys. You may 
   need to edit it, for example to give the correct library path for your 
   machine.
   
    On a linux system with the intel compiler build Wannier90 by typing

         cp ./config/make.sys.intel ./make.sys
         make 

   Options to make include:

   make wannier    (default) build the wannier90 executable
   make lib        build the wannier90 library
   make test       run test cases
   make doc        build the documentation
   make dist       make a tar-ball of the distribution
   make dist-lite  make a tar-ball of the src and tests only
   make clean      remove object files etc

 
 Compiler: If your operating system came with a Fortran compiler or you have a
 commercial compiler (such as ifort) this should give the best performance.
 The g95 compiler is available for many operating systems (inc Windows) and 
 should give 50% - 75% the performance of the commercial compilers. 
 http://www.g95.org We used g95 a lot when writing Wannier90. 
 It's a really good compiler to develop code with.
  
 Libraries: For Wannier90 to perform well a well optimised BLAS library should
 be used. Many commercial operating systems and compilers provide well optimised
 BLAS libraries.
  ATLAS is one of the fastest implementations
     http://math-atlas.sourceforge.net/
  GOTO BLAS provides optimised routines for many architecture
     http://www.tacc.utexas.edu/resources/software/
  ACML AMD provides optimised BLAS for AMD processors 
    http://developer.amd.com/acml.aspx  
  LAPACK can be obtained from the netlib website. It also includes a 
  non-optimised BLAS.
     http://www.netlib.org/lapack/
     

Linux x86,x86-64
----------------

  1- make.sys.intel
     Compiler:  Intel (ifc,ifort,iforte)
     Libraries: Intel mkl
                (ATLAS BLAS is faster for AMD processors) 
**Note: we have found an issue with ifort and ATLAS3.8.0. In certain cases BLAS calls return
  NANs. The origin of this is unclear - we'd welcome any further reports.**

  2- make.sys.pathscale
     Compiler:  Pathscale (pathf90)
     Libraries: acml 

  3- make.sys.nag   
     Compiler:  NAG (f95)
     Libraries: ATLAS + LAPACK (maybe acml)
 [note in our experience the NAG compiler does not produce well optimised code]

  4- make.sys
     Compiler: Sun-studio f90
     Libraries: sunperf (ATLAS is faster)
     avaible as a free beta for Linux

Generic: Most architectures
---------------------------
  1- make.sys.g95
     Compiler: g95
     Libraries: ATLAS + LAPACK

  2- make.sys.gfort
     Compiler: gfortran
     Libraries: ATLAS + LAPACK
     (the official gcc f90 compiler - often faster than g95)


Alpha/HP/Compaq/DEC Tru64 UNIX
------------------------------

   1- make.sys.alpha
      Compiler: f90
      Libraries: cxml

Sun / Solaris  (sparc or x86)
----------------------------

   1- make.sys.sun
      Compiler: f95
      Libraries: sunperf

IBM PowerPC/power series. Linux or AIX
--------------------------------------

  1- make.sys.xlf
     Compiler:  xlf95
     Libraries: ESSL + LAPACK
       Note: ESSL does not provide a complete lapack installation.
         If your machine does not have a full LAPACK install, 
         download the netlib LAPACK. You might want to use
         the essl wrappers from 
         http://www.netlib.org/lapack/essl/

Windows
-------
 There are many commercial Fortran compilers for windows.
 We haven't included make.sys files for these as we don't 
 have access to them. Wannier90 should compile just fine.

 I use cygwin (http://www.cygwin.com/) which provides a bash shell.

  1- make.sys.g95
     Compiler: g95  (within cygwin)
     Libraries: LAPACK and ATLAS (cygwin comes with a lapack and blas library,
     but I think they have been compiled with g77. I had problems making 
     a working executable. I suggest building your own)

 2- make.sys.pgf90
    Compiler: Portland Group (pgf90)
    Libaries: pg supplied lapack and blas