 8554 (1997)).

<P>
The keyword <code>beckehandh</code> specifies that the exchange-correlation energy will be
computed as 
<P></P>
<DIV ALIGN="CENTER">
<!-- MATH
 \begin{eqnarray*}
E_{XC} \ \approx \ \frac{1}{2} E^{\rm HF}_X + \frac{1}{2} E^{\rm   Slater}_{X} + \frac{1}{2} E^{\rm PW91LDA}_{C}
\end{eqnarray*}
 -->
<IMG
 WIDTH="290" HEIGHT="89" BORDER="0"
 SRC="img108.gif"
 ALT="\begin{eqnarray*}
E_{XC} \ \approx \ \frac{1}{2} E^{\rm HF}_X + \frac{1}{2} E^{\rm Slater}_{X} + \frac{1}{2} E^{\rm PW91LDA}_{C}
\e