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<div class="moz-cite-prefix">For each constant of a (a1-a5), you
should only have one number.<br>
<br>
If I remember correctly, this happens when you do not use 5
points.<br>
<br>
In other words, you must have only 5 case_coa___*.scf files in
your case directory. Keep the five case_coa___*.scf files closest
to the minimum. Move (or delete) the other case_coa___*.scf
files. Then, plot E vs. c/a again.
[<a class="moz-txt-link-freetext" href="http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg05826.html">http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg05826.html</a>]<br>
<br>
On 1/24/2014 7:29 PM, Lawal Mohammed wrote:<br>
</div>
<blockquote
cite="mid:1390616986.2732.YahooMailNeo@web125703.mail.ne1.yahoo.com"
type="cite">
<div style="color:#000; background-color:#fff;
font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial,
Lucida Grande, sans-serif;font-size:10pt">Dear Gavin Abo, Sir,<br>
<br>
In line with the discussion above, I got when I plot E vs c/a
the following<br>
<br>
<span style="font-weight: bold;">Fit of: E = a1 + a2*x + a3*x^2
+ a4*x^3 + a5*x^4<br>
a1<span class="tab"> <span class="tab"> <span
class="tab"> <span class="tab"> <span
class="tab"> </span></span></span></span>1.000<br>
</span>a2<span class="tab"> <span class="tab"> <span
class="tab"> <span class="tab"> <span
class="tab"> <span class="tab">0.000<span
class="tab"> 1.000</span></span></span></span></span></span></span><br>
a3<span class="tab"> <span class="tab"> <span
class="tab"> <span class="tab"> <span
class="tab"> -0.761 -0.000<span class="tab">
1.000</span></span></span></span></span></span><br>
a4<span class="tab"> <span class="tab"> <span
class="tab"> <span class="tab"> <span
class="tab"> -0.000<span class="tab"> -0.930<span
class="tab"> 0.000<span class="tab"> 1.000</span></span></span></span></span></span></span></span><br>
a5</span><span class="tab"><span style="font-weight: bold;">
</span><span class="tab"><span style="font-weight: bold;">
</span><span class="tab"><span style="font-weight: bold;">
</span><span class="tab"><span style="font-weight: bold;">
</span><span class="tab"><span style="font-weight:
bold;"> 0.642</span><span class="tab"><span
style="font-weight: bold;"> </span><span
class="tab"><span style="font-weight: bold;">0.000<span
class="tab"> -0.972<span class="tab">
-0.000<span class="tab"> 1.000</span></span></span>
<br>
</span><br>
In this case what should be the value for a2, a3,
a4, and a5? <br>
<br>
Thank you in advance for your response.<br>
With kind regards<br>
Mohammed Lawal <br>
</span></span></span></span></span></span></span>
<div><span><br>
</span></div>
<div style="display: block;" class="yahoo_quoted"> <br>
<br>
<div style="font-family: HelveticaNeue, Helvetica Neue,
Helvetica, Arial, Lucida Grande, sans-serif; font-size:
10pt;">
<div style="font-family: HelveticaNeue, Helvetica Neue,
Helvetica, Arial, Lucida Grande, sans-serif; font-size:
12pt;">
<div dir="ltr"> <font face="Arial" size="2"> On Friday,
January 24, 2014 7:08 AM, Gavin Abo
<a class="moz-txt-link-rfc2396E" href="mailto:gsabo@crimson.ua.edu"><gsabo@crimson.ua.edu></a> wrote:<br>
</font> </div>
<div class="y_msg_container">
<div id="yiv8953273078">
<div>
<div class="yiv8953273078moz-cite-prefix">Below is a
summary of previous posts that should help.<br
clear="none">
<br clear="none">
To plot energy vs b/a:<br clear="none">
<br clear="none">
(a) You should be able to rename the scf files and
then plot with the energy vs c/a option of eplot
[<a moz-do-not-send="true" rel="nofollow"
shape="rect"
class="yiv8953273078moz-txt-link-freetext"
target="_blank"
href="http://zeus.theochem.tuwien.ac.at/pipermail/wien/2009-January/012053.html">http://zeus.theochem.tuwien.ac.at/pipermail/wien/2009-January/012053.html</a>].<br
clear="none">
(b) You could also plot energy vs b/a in another
program like Origin
[<a moz-do-not-send="true" rel="nofollow"
shape="rect"
class="yiv8953273078moz-txt-link-freetext"
target="_blank"
href="http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg08841.html">http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg08841.html</a>].<br
clear="none">
<br clear="none">
To get the optimized c/a (or b/a) value, you can
calculate it from the curve fit equation
[<a moz-do-not-send="true" rel="nofollow"
shape="rect"
class="yiv8953273078moz-txt-link-freetext"
target="_blank"
href="http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg05826.html">http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg05826.html</a>].<br
clear="none">
<br clear="none">
An example calculation is given below.<br
clear="none">
<br clear="none">
When you plot E vs. c/a with eplot, you should get
something like:<br clear="none">
<br clear="none">
Fit of: E = a1 + a2*x + a3*x^2 + a4*x^3 + a5*x^4<br
clear="none">
a1 = -2201.24<br clear="none">
a2 = 0.00233422<br clear="none">
a3 = 0.000188276<br clear="none">
a4 = 1.33462e-05<br clear="none">
a5 = 9.76521e-07<br clear="none">
<br clear="none">
From dE/dx = 0, we get the equation:<br
clear="none">
<br clear="none">
a2 + 2*a3*x+3*a4*x^2+4*a5*x^3 = 0<br clear="none">
<br clear="none">
Solving this equation for x, x = -7.7555, which is
the optimized c/a ratio in %. I got x with
Octave, but there are other software programs that
you can find on the internet to solve the
polynomial equation.<br clear="none">
<br clear="none">
Octave input:<br clear="none">
<br clear="none">
dEdx =
[4*9.76521e-07,3*1.33462e-05,2*0.000188276,0.00233422]<br
clear="none">
roots(dEdx)<br clear="none">
<br clear="none">
Octave output:<br clear="none">
<br clear="none">
-1.2474 + 8.6889i<br clear="none">
-1.2474 - 8.6889i<br clear="none">
-7.7555 + 0.0000i <= This polynomial root is
chosen as x, because the imaginary part is zero
and it appears in the energy vs c/a plot.<br
clear="none">
<br clear="none">
If you also want the minimum E, just plug the x
value back into the curve fit equation and solve
for E (= -2201.2495).<br clear="none">
<br clear="none">
On 1/22/2014 7:22 AM, MAHDI SALMANI HIRMAND wrote:<br
clear="none">
</div>
<div class="yiv8953273078yqt2770598339"
id="yiv8953273078yqt63325">
<blockquote type="cite">
<div
style="color:#000;background-color:#fff;font-family:HelveticaNeue,
Helvetica Neue, Helvetica, Arial, Lucida
Grande, sans-serif;font-size:12pt;">
<div>Dear Prof. Blaha,</div>
<div>Please let me know why there is not a
program for finding minimum of c/a or b/a
ratio with Wien2k Package when we optimize
c/a or b/a.</div>
<div>eplot program can show curve of Energy
Vs. c/a but it doesn't find minimum of c/a.</div>
<div>Please guide me</div>
<div>With best</div>
<div>Mahdi</div>
</div>
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