ork, 1974)), and the correlation functional is the Vosko-Wilk-Nusair
(VWN) functional (functional V) (S.J.&nbsp;Vosko, L.&nbsp;Wilk and M.&nbsp;Nusair,
Can.&nbsp;J.&nbsp;Phys.&nbsp;<B>58</B>, 1200 (1980)).  The parameters used in this
formula are obtained by fitting to the Ceperley and
Alder<A NAME="tex2html29"
  HREF="footnode.html#foot3424"><SUP>11.2</SUP></A>Quantum Monte-Carlo solution of the <EM>  homogeneous electron gas</EM>.

<P>
These defaults can be invoked explicitly by specifying the following
k