positions.html

<H1><B><FONT size="+0">Specification of site positions</FONT></B></H1>

The LMTO programs read site positions in different ways.

Initially site positions are read through the input file, in the site
category through the token
<pre>
  POS= x y z
</pre>
The input file can however specify the that the positions be read from
a <B>site file</B>, through the token
<pre>
  FILE= file-name
</pre>
If this token is present in the <B>SITE</B> category, it takes precedence.

Next, the positions information can be overwritten by the command-line
argument
<pre>
  --rpos=file-name
</pre>
which reads a file containing atom positions.

Next, the entire lattice, including the site positions, can be rotated or
otherwise subject to a linear transformation as specified in the <B>STRUC</B>
category.  Tokens in <B>STRUC</B> that generate a linear transformation are:
<pre>
  SHEAR=   a volume-conserving shear transformation
  ROT=     a rigid rotation
  DEFGRD=  a 3x3 matrix specifying a general linear transformation
  STRAIN=  a Voigt strain
</pre>
Each of these tokens is described in <B><A
href="lmto.html">lmto.html</A></B>; see also <B><A
href="rotations.html">rotations.html</A></B> for the syntax to specify
a rigid rotation.

<P>

Finally, if a restart file is read, the site positions are once again
overwritten from data in the restart file, unless you specifically
specify that it not do so.  The restart file checks to see if the
lattice vectors it contains differ from those specified in the input
file.  If there is a difference, it will rotate the site postions by
the linear transformation that changes the input file's lattice
vectors into the restart file's lattice vectors.