<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;"><p style="margin-bottom: 0in; font-weight: bold;"><font size="5">Dear All<br></font></p><p style="margin-bottom: 0in; font-weight: bold;"><font size="5">I want to calculate lattice constants
a, and c and bulk modulus of w-ZnO. For this purpose:</font></p>
<ol><li style="font-weight: bold;"><p style="margin-bottom: 0in;"><font size="5">I take experimental lattice
constants (a= 3.25 Ang. and c = 5.206 Ang. and by changing these values into bohr.) and first take different
values above and below a and do scf calculations to optimize a. As
in case of W ZnO (Hexagonal and Trigonal P) ibrav= 4 and celldm(3)
=c/a is used. So when I change a (celldm (1))I have to change celldm
(3). In this way I get lattice constant a which is nearly same as
experimental with 2 percent error.
</font></p>
</li><li style="font-weight: bold;"><p style="margin-bottom: 0in;"><font size="5">Then I fix this lattice constant a
(celldm (1)) and change lattice constant c (By taking different
values above and below experimental value of c). As c changes celldm
(3) also changes. In this way I get lattice constant c which is very
close to experimental lattice constant with a little error of 2
percent.</font></p>
</li><li style="font-weight: bold;"><p style="margin-bottom: 0in;"><font size="5">The output data for the
calculation of c by fixing a I use to calculate BULK modulus for
ZnO. Again these results are comparable with experimental and already calculated
results by different techniques .</font></p>
</li><li><p style="margin-bottom: 0in; font-weight: bold;"><font size="5">Now I want to know that, Is my
calculation procedure is right?</font></p>
</li></ol>
<span style="font-weight: bold;">Best Regards</span><br><br>Muhammad Zafar<br>
PhD Scholar<br>
Department of Physics<br>
The Islamia University of Bahawalpur,Pakistan</td></tr></table>