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|               PL_assess.f90               |
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|        Written by M.Shelley 09/09         |
|         Imperial College, London          |
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Function: To assess principal layer size of a 
          system from a single cell many 
          k-point calculation.

Requirements: <seedname>_hr.dat

Usage: Copy hr file to directory containing 
       executable. Within that directory, 
       type:

./PL_assess.x <nk1> <nk2> <nk3> <num_wann> 

where:

 <nk1> is the number of k-points in x-direction
 <nk2> is the number of k-points in y-direction
 <nk3> is the number of k-points in z-direction
 <num_wann> is the number of wannier functions of your system

    Note currently, only one k-point in non-transport directions
    is accepted.


eg.  ./PL_assess.x 1 1 20 16

When prompted, enter the seedname.

Result: <seedname>_pl.dat written. It contains 3 coloumns
        (1): Unit cell number
        (2): Average 'on-site' between Wannier functions in 
             true unit cell, and unit cell (1) away due to 
             k-point 'periodicity'
        (3): Standard devaition of (2)
        (4): Maximum absolute Hamiltonian value in unit cell