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Actually it's<br>
<blockquote>cos(alpha) = <b>b</b> . <b>c</b> / ( |<b>b</b>||<b>c</b>|
)<br>
</blockquote>
Éric.<br>
<br>
On 11/17/2011 12:49 AM, Huiqun Zhou wrote:
<blockquote cite="mid:333916570C304FBE95176B9CEF256B1F@solarflare"
type="cite">
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<div><font face="Arial" size="2">I'm afraid the formula for
calculating cosA should be</font></div>
<div><font face="Arial" size="2">cosA = b (*) c / (|b| | c|)</font></div>
<div> </div>
<div><font face="Arial" size="2">dr. zhou huiqun</font></div>
<div><font face="Arial" size="2">@earth sciences, nanjing
university, china</font></div>
<div> </div>
<blockquote style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT:
5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<div style="FONT: 10pt arial">----- Original Message ----- </div>
<div style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color:
black"><b>From:</b> <a moz-do-not-send="true"
title="flux_ray12@163.com" href="mailto:flux_ray12@163.com">GAO
Zhe</a> </div>
<div style="FONT: 10pt arial"><b>To:</b> <a
moz-do-not-send="true" title="pw_forum@pwscf.org"
href="mailto:pw_forum@pwscf.org">PWSCF Forum</a> </div>
<div style="FONT: 10pt arial"><b>Sent:</b> Wednesday, November
16, 2011 8:53 PM</div>
<div style="FONT: 10pt arial"><b>Subject:</b> Re: [Pw_forum]
calculation of lattice parameter and angle of rhombohedral
structure</div>
<div><br>
</div>
<div style="LINE-HEIGHT: 1.7; FONT-FAMILY: arial; COLOR:
#000000; FONT-SIZE: 14px">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>
<br>
At 2011-11-16
20:14:38,"yedu kondalu" <a class="moz-txt-link-rfc2396E" href="mailto:nykondalu@gmail.com"><nykondalu@gmail.com></a> wrote:<br>
<blockquote style="BORDER-LEFT: rgb(204,204,204) 1px solid;
MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex"
id="isReplyContent">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>
</blockquote>
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<br>
<a
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Éric Germaneau</a><br>
<br>
Graduate University of Chinese Academy of Sciences<br>
College of Physical Sciences<br>
Yuquan Road 19A<br>
Beijing 100049<br>
China<br>
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