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Dear Kondal,<br>
<br>
The first line of the matrix correspond to <b>a</b>, the second to
<b>b</b>, and the third to <b>c</b>.<br>
In order to get a, b, and c, just calculate the norm of the
corresponding vectors. <br>
Don't forget to multiply by alat to have them in Bohr.<br>
Then, <i>alpha</i> is the angle between vectors <b>b</b> and <b>c</b>,
so you just need to calculate the dot product <b>b.c</b>. <br>
You'll get <i>alpha</i> by doing <br>
<blockquote><i>alpha</i> = acos( <b>b.c</b> / b*c )<br>
</blockquote>
Finally, just do the same thing for <i>beta</i>, the angle between
<b>a</b> and <b>c</b>, and <i>gamma</i>, the angle between <b>a</b>
and <b>b</b>.<br>
<br>
Hope it helps,<br>
<br>
Éric.<br>
<br>
On 12/27/2011 01:05 AM, yedu kondalu wrote:
<blockquote
cite="mid:CABJwmWdtniECxe8MgwwTRHqyN1oixE10gqaPQrafujmhDvBr5g@mail.gmail.com"
type="cite">Dear users,<br>
<br>
I did the structural optimization of a compound belongs to
the space group <i><b>Ibam</b><b>-72</b></i> (body centred
orthorhombic) using variable cell (vc-relax) method. <br>
<br>
lattice parameter (alat) = 10.5862 a.u.<br>
unit-cell volume = 675.9126 (a.u.)^3<br>
<br>
The initial basis vectors <br>
a(1) = ( 0.500000 0.529989 0.537487 ) <br>
a(2) = ( -0.500000 0.529989 0.537487 ) <br>
a(3) = ( -0.500000 -0.529989 0.537487 ) <br
clear="all">
<br>
After the structural optimization the vectors are<br>
<br>
new unit-cell volume = 614.83507 a.u.^3 ( 91.10916 Ang^3 )<br>
<br>
CELL_PARAMETERS (alat= 10.58624499)<br>
0.529016060 0.479936985 0.510293152<br>
-0.529016060 0.479936985 0.510293152<br>
-0.529016060 -0.479936985 0.510293152<br>
<br>
1. How to calculate the lattice parameters for this case ?<br>
<br>
2. How to do the same for all the non cubic systems ? <br>
<br>
Can some body please explain me any method or reference books to
do the same ?<br>
<br>
<br>
Thanking you<br>
<br>
Regards<br>
KONDAL<br>
<br>
<br>
<br>
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<br>
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<br>
<a
href="http://www.linkedin.com/pub/%C3%A9ric-germaneau/30/931/986">Dr.
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>
<br>
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