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       g_nmeig - diagonalizes the Hessian

       VERSION 4.0.1


       g_nmeig  -f hessian.mtx -s topol.tpr -of eigenfreq.xvg -ol eigenval.xvg
       -v eigenvec.trr -[no]h -nice int -[no]xvgr -[no]m -first int -last int


       g_nmeig calculates the eigenvectors/values of a (Hessian) matrix, which
       can  be  calculated  with   mdrun.   The  eigenvectors are written to a
       trajectory file ( -v).  The structure is written first  with  t=0.  The
       eigenvectors  are  written  as  frames  with  the eigenvector number as
       timestamp.  The  eigenvectors  can  be  analyzed  with   g_anaeig.   An
       ensemble  of  structures  can  be generated from the eigenvectors with
       g_nmens. When mass weighting is used, the generated  eigenvectors  will
       be  scaled  back  to  plain cartesian coordinates before generating the
       output - in this case they will no longer be exactly orthogonal in  the
       standard  cartesian norm (But in the mass weighted norm they would be).


       -f hessian.mtx Input
        Hessian matrix

       -s topol.tpr Input
        Structure+mass(db): tpr tpb tpa gro g96 pdb

       -of eigenfreq.xvg Output
        xvgr/xmgr file

       -ol eigenval.xvg Output
        xvgr/xmgr file

       -v eigenvec.trr Output
        Full precision trajectory: trr trj cpt


        Print help info and quit

       -nice int 19
        Set the nicelevel

        Add specific codes (legends etc.) in the  output  xvg  files  for  the
       xmgrace program

        Divide  elements of Hessian by product of sqrt(mass) of involved atoms
       prior to diagonalization.  This  should  be  used  for  ’Normal  Modes’

       -first int 1
        First eigenvector to write away

       -last int 50
        Last eigenvector to write away



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                                Thu 16 Oct 2008                     g_nmeig(1)