<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>Il giorno 06/lug/09, alle ore 10:06, ali kazempour ha scritto:</div><blockquote type="cite"><table cellspacing="0" cellpadding="0" border="0" style="position: static; z-index: auto; "><tbody><tr><td valign="top" style="font: inherit;"><br>Dear all<br>I want to study the effect of U(habburd parameter on band gap). According to method described in coccocini phd thesis , we are able to obtain U by setting alpha to different values and the difference in the slope of ns Vs. alpha and ns0 Vs. alpha0 is U parameter.<br>My question is : Do I Optimize the lattice constant After obtaining U from above procedure or not?<br>Does above method works for any bulk material that have d orbital? </td></tr></tbody></table></blockquote></div><br><div>I think that in principle the correct procedure should be to recompute U for every lattice parameter value you will use to get the total energy and then fit to the equation of state. This is because of the internally consistent definition of U, which depends on the local environment surrounding the Hubbard atoms. At each value of the lattice parameter this environment changes, and the hybridization of the Hubbard orbitals is influenced by it. Anyway I guess that if you computed the U at a value of the lattice parameter not distant from the optimal one (theoretical), maybe you can use that value of U to get the total energy in the neighborhood of the optimal value. On the contrary, the estimation of the bulk modulus may be much more sensitive of the value of U which you employ.</div><div><br></div><div><br></div><div>GS</div><div apple-content-edited="true"> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 16px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 16px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div><i><br class="Apple-interchange-newline"><br class="Apple-interchange-newline"><font class="Apple-style-span" color="#7E7E7E">Gabriele Sclauzero, PhD Student</font></i></div><div><i><font class="Apple-style-span" color="#7E7E7E"> SISSA & CNR-INFM Democritos,</font></i></div><div><i><font class="Apple-style-span" color="#7E7E7E"> via Beirut 2-4, 34014 Trieste (Italy)</font></i></div><div><i><font class="Apple-style-span" color="#7E7E7E"> email: <a href="mailto:sclauzer@sissa.it">sclauzer@sissa.it</a> </font></i></div><div><i><font class="Apple-style-span" color="#7E7E7E"> phone: +39 040 3787 511</font></i></div><div><i><font class="Apple-style-span" color="#7E7E7E"> skype: gurlonotturno</font></i></div><div><br></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"> </div><br></body></html>