<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:13px"><div id="yiv6514460529"><div id="yui_3_16_0_1_1442335522971_2626"><div id="yui_3_16_0_1_1442335522971_2625" style="color:#000;background-color:#fff;font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:13px;"><div dir="ltr" id="yiv6514460529yui_3_16_0_1_1442312681269_15331"><div id="yui_3_16_0_1_1442335522971_3073"><font face="verdana, helvetica, sans-serif">Dear Developers and Users,</font></div><div id="yui_3_16_0_1_1442335522971_3104"><font face="verdana, helvetica, sans-serif"><br></font></div><div id="yui_3_16_0_1_1442335522971_3105"><font face="verdana, helvetica, sans-serif">I need some guidance.<br></font></div></div><div id="yiv6514460529yui_3_16_0_1_1442312681269_15326"><font face="verdana, helvetica, sans-serif"><br></font></div><div id="yiv6514460529yui_3_16_0_1_1442312681269_16401"><div id="yui_3_16_0_1_1442335522971_3251"><font face="verdana, helvetica, sans-serif">I understand that in gga/lda the Kohn-Sham eigenstates are regarded as excited only when the scissors operator is non zero, is this correct? <br></font></div><div dir="ltr" id="yui_3_16_0_1_1442335522971_3260"><font id="yui_3_16_0_1_1442335522971_4757" face="verdana, helvetica, sans-serif">If yes then how valid is optical calculation when the scissors operator is set to zero? If no then what bring about the optical excitations that allow determination of some optical properties?<br></font></div><div id="yui_3_16_0_1_1442335522971_3505" dir="ltr"><font id="yui_3_16_0_1_1442335522971_4759" face="verdana, helvetica, sans-serif"><br class="" id="yui_3_16_0_1_1442335522971_3481">Thanks in advance....<br></font></div></div><div id="yiv6514460529yui_3_16_0_1_1442312681269_15327"><font face="verdana, helvetica, sans-serif"><br></font></div><font face="verdana, helvetica, sans-serif">With Kind regards</font><br><div id="yiv6514460529yui_3_16_0_1_1442312681269_15261" class="yiv6514460529signature"><div id="yiv6514460529yui_3_16_0_1_1442312681269_15260"><font id="yui_3_16_0_1_1442335522971_3507" face="verdana, helvetica, sans-serif" size="3"><i id="yui_3_16_0_1_1442335522971_3506">Lawal Mohammed</i></font></div><h4 id="yiv6514460529yui_3_16_0_1_1442312681269_15264"><br></h4></div></div></div></div></div></body></html>