<TABLE id=HB_Mail_Container height="100%" cellSpacing=0 cellPadding=0 width="100%" border=0 UNSELECTABLE="on">
<TBODY>
<TR height="100%" width="100%" UNSELECTABLE="on">
<TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNSELECTABLE="off">
<DIV>
<TABLE class=messageheader cellSpacing=0 cellPadding=0 width="100%" border=0>
<TBODY>
<TR>
<TD></TD></TR>
<TR>
<TD class=label noWrap></TD>
<TD></TD></TR></TBODY></TABLE>
<FORM name=frmAddAddrs action=http://address.mail.yahoo.com/yab/us?v=YM&.rand=55704&A=m&simp=1 method=post> </FORM>
<DIV id=message>
<TABLE id=HB_Mail_Container height="100%" cellSpacing=0 cellPadding=0 width="100%" border=0 UNSELECTABLE="on">
<TBODY>
<TR height="100%" width="100%" UNSELECTABLE="on">
<TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNSELECTABLE="off">
<DIV>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN lang=EN-GB><FONT face="Times New Roman">Dear wien users,</FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN lang=EN-GB><FONT face="Times New Roman"> <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN lang=EN-GB><FONT face="Times New Roman">I am calculating the optical conductivity of bcc iron<SPAN style="mso-spacerun: yes"> </SPAN>and found that the absorptive part is not always positive. This means that a plot of Re_sigma_xx<SPAN style="mso-spacerun: yes"> </SPAN>Re_sigma_yy<SPAN style="mso-spacerun: yes"> </SPAN>Re_sigma_zz<SPAN style="mso-spacerun: yes"> </SPAN>using<SPAN style="mso-spacerun: yes"> </SPAN>file fe.absorpup has a negative part between 2.7eV and about 14.0eV. I think this is strange. This is because the mathematical expression (per spin) for<SPAN style="mso-spacerun: yes"> </SPAN>Re_sigma_xx<SPAN style="mso-spacerun: yes"> </SPAN>etc. makes it impossible for it to be negative.<SPAN style="mso-spacerun: yes"> </SPAN></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN lang=EN-GB><FONT face="Times New Roman"> <o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN lang=EN-GB><FONT face="Times New Roman">Thanks.</FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN lang=EN-GB><FONT face="Times New Roman"> <o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN lang=EN-GB><FONT face="Times New Roman">C M I Okoye</FONT></SPAN></P></DIV></TD></TR></TBODY></TABLE></DIV></DIV></TD></TR>
<TR UNSELECTABLE="on" hb_tag="1">
<TD style="FONT-SIZE: 1pt" height=1 UNSELECTABLE="on">
<DIV id=hotbar_promo></DIV></TD></TR></TBODY></TABLE><BR><BR><TABLE id=HB_Mail_Container height="100%" cellSpacing=0 cellPadding=0 width="100%" border=0 UNSELECTABLE="on">
<TBODY>
<TR height="100%" width="100%" UNSELECTABLE="on">
<TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNSELECTABLE="off">
<P><FONT face=courier>Chukwu<STRONG>emeka</STRONG> M I Okoye</FONT></P>
<P><FONT face=courier>Department of Physics and Astronomy,</FONT></P>
<P><FONT face=courier>University of Nigeria,Nsukka,</FONT></P>
<P><FONT face=courier>Enugu State, <STRONG>Nigeria</STRONG>.</FONT></P>
<P><FONT face=courier>+2348045257257</FONT></P>
<P><FONT face=courier>+234 42 771611</FONT></P></TD></TR>
<TR UNSELECTABLE="on" hb_tag="1">
<TD style="FONT-SIZE: 1pt" height=1 UNSELECTABLE="on">
<DIV id=hotbar_promo></DIV></TD></TR></TBODY></TABLE>
<BLOCKQUOTE id=45db1896>
<DIV> </DIV></BLOCKQUOTE>