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Hello everyone,<br>
Problem 1<br>
---------------------------------------<br>
I'm computing for lattice constant and comparing the employment of
exchange correlation ultra-soft pp such as LDA, PBE and PBEsol. I
know LDA would underestimate the lattice parameter, PBE would
overestimate it but PBEsol should do better than PBE.<br>
<br>
My calculations are shows LDA=
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<font style="font-size: 11pt" size="3">3.419 </font>PBE=
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<font style="font-size: 11pt" size="3">3.516</font> PBEsol = 3.455
Angstom. experimnetal value I'm comparing it to is 3.522 Ang<br>
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-PBE= 3.455</style>
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--> </style>PBEsol gave a lower atomic lattice value than PBE.<br>
<br>
What could be wrong with the composition of the system?<br>
<br>
Attached is the input file(vc_ni-bulk-pbesol.in) for the PBEsol USPP
calculations. <br>
<br>
Problem 2<br>
-------------------------------------------<br>
Trying to find Cohesive energy and I already have my energy of the
bulk.<br>
I'm now computing for the energy of a single atom in a vacuum
system.<br>
<br>
I added 15 15 15 Ang to the XYZ Cell parameters and the single atom
sits in a corner whiles I expect it to sit some where in the middle.
<br>
<br>
What I'm I not doing right please. <br>
<br>
Attached is the respective (evac-ni.in) file too. <br>
Thank you.<br>
<br>
<br>
<br>
<br>
Kind Regards,<br>
<br>
<br>
<br>
Elliot<br>
<br>
<pre class="moz-signature" cols="72">--
Elliot S. Menkah
Research Student - Computational Chemistry/ Computational Material Science
Theoretical and Computational Chemistry
Dept. of Chemistry
Kwame Nkrumah UNiversity of Sci. and Tech.
Kumasi
Ghana
Tel: +233 243-055-717
Alt Email: <a class="moz-txt-link-abbreviated" href="mailto:elliotsmenkah@gmail.com">elliotsmenkah@gmail.com</a>
<a class="moz-txt-link-abbreviated" href="mailto:elliotsmenkah@hotmail.com">elliotsmenkah@hotmail.com</a>
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