<div>hi ,uesers here :</div>
<div>i relax one crystal lattice vs energy:</div>
<div>i have compute several energy list :</div>
<div> </div>
<div>c E(RY)</div>
<div>2.795 -137.79266<br>2.78 -137.79248<br>2.77 -137.79233<br>2.8 -137.7927<br>2.81 -137.79275<br>2.82 -137.79275<br>2.83 -137.79278<br>2.84 -137.79276<br>2.85 -137.79279<br>2.86 -137.79272<br>2.87 -137.79265
<br>2.88 -137.79258<br>2.9 -137.79229<br>2.95 -137.79122</div>
<div>these energy points are smooth and can be plotted parabola.<br>the system has 12 atoms.the energy is different most at the third digit after radix point. so i think the average energy/atom is less 0.0001.</div>
<div><br clear="all">i want to ask the within the precision of energy(my thinking is based on that :my above calculation is set ecutwfc:29, ecutrho:200,and the criterion is 35,350, the convergence is <span lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: ËÎÌå; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">
0.0049345 ry.)</span></div>
<div><span lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: ËÎÌå; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">
so </span>this small difference of energy can skip,i.e we can choose 2.77 which is regarded as the best structure?</div>
<div> as why i ask this question,for the the structure of 2.85 has two big negative frequencies near -100cm-1, even if i add asr .</div>
<div>but 2.77 has no negative frequency after i add asr.</div>
<div> </div>
<div><br>-- <br>Xu Yuehua<br>physics Department of Nanjing university<br>China </div>