How to find the lattice parameters for monoclinic?

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magnones
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How to find the lattice parameters for monoclinic?

#1 Post by magnones » Sat May 26, 2007 10:40 pm

hi all

well this is an old problem that i have. I have a monoclinic structure whit three lattice paramenters a.b and c and 12 ions postions for my structure. I read from the VASP manual that for a cubic strcture it is easy it is only necesary to make a scan of energies vs lattice parameter (in this case the only degree of freedom) . I need to find the optimal parameters for the three lattice parameters so that i can get the graphic E vs V in order to fit it to a murnhghan equation (the same way i did for the cubic). in order to do that i did the following in my poscar: I divide the lattice parameters in this case by the first parameter "a" so i get a psocar likie this


#!/bin/bash
rm WAVECAR
for i in 5.0 5.10 5.11 5.12 5.13 5.14 5.15 5.17 5.2 5.3 5.4
do
cat >POSCAR << !
Monoclinico
1
$i 0.00000000 0.00000000
0.00000000 5.20750000 0.00000000
-0.85213078 0.00000000 5.24188970
4 8
Directas
0.27580000 0.04040000 0.20890000
-0.27580000 0.54040000 0.29110000
-0.27580000 -0.04040000 -0.20890000
.
......

the scan for the lattice parameters around 20% of the expermintal parameter. It is ok what i am doing?, If it is not What could i do to optimize my parameters and find the E vs v graphics in order to fit it to a murnaghan equation to get strctural parameters ?


i would be very thankful for some help

thak you in advance
Last edited by magnones on Sat May 26, 2007 10:40 pm, edited 1 time in total.

support_vasp
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Re: How to find the lattice parameters for monoclinic?

#2 Post by support_vasp » Wed Sep 11, 2024 1:47 pm

Hi,

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