<div style="line-height:1.7;color:#000000;font-size:14px;font-family:arial">the three basis vectors of rhombohedral are (after relaxation) :<br>a = ( 0.636439417 -0.367448469 0.640642896 )<br>b = ( 0.000000000 0.734896938 0.640642896 )<br>c = ( -0.636439417 -0.367448469 0.640642896 )<br>then the lattice paremeter should be: A = sqrt (a1^2+a2^2+a3^2) * alat = 8.05092296 a.u. .<br>The angle between two vectors can be calculated by:<br>cosA = a (*) b / |a (*) b|,<br>where a and b are basis vectors, (*) represents the dot product.<br><br><div>--<br>GAO Zhe<br>CMC Lab, MSE, SNU, Seoul, S.Korea<br>
</div><div id="divNeteaseMailCard"></div><br>At 2011-11-16 20:14:38,"yedu kondalu" <nykondalu@gmail.com> wrote:<br> <blockquote id="isReplyContent" style="padding-left: 1ex; margin: 0px 0px 0px 0.8ex; border-left: 1px solid rgb(204, 204, 204);">Dear users,<br><br> I did the optimization for a compound using variable cell approximation using PWSCF, which belongs to the space group R3m(160) Rhombohedral representation. The primitive vectors in terms of lattice parameter a = 8.25791360 a.u. <br>
a(1) = ( 0.619505 -0.357671 0.698774 ) <br> a(2) = ( 0.000000 0.715343 0.698774 ) <br> a(3) = ( -0.619505 -0.357671 0.698774 ) <br><br>after completion of optimization step, the primitive vectors<br>
<br>CELL_PARAMETERS (alat= 8.25791360)<br> 0.636439417 -0.367448469 0.640642896<br> 0.000000000 0.734896938 0.640642896<br> -0.636439417 -0.367448469 0.640642896<br><br>can u please explain me <br><br>how can I calculate the lattice parameter <b>a</b> and the <b>angle (alpha)</b> ???<br>
<br>Thanks in advance<br><br> Regards<br> Yedukondalu<br><br><br>
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