On 02/05/2014 10:56 AM, Ganjar Kurniawan wrote: > I am trying to compare the calculation of the Lithium bulk system > which has BCC structure with lattice constant is 6.597 bohr using > different pseudopotential between Li.pbe-s-rrkjus_psl.0.2.1.UPF and > Li.pw91-n-van.UPF. > > the result give different of total energy are -14.82521305 Ry and > -1.82426227 Ry respectively... > > The question is why this is happen??? anyone can to explain it??? > Dear Ganjar, as often repeated, the absolute value of the total energy has no meaning in periodic boundary condition and pseudopotential calculations. Only relative energy, computed with strictly the same setup have physical meaning.
I.e. in your case you an compare the energy of bulk Lithium with that of isolated Lithium atoms, computed with the same pseudo and cutoff. This would give you the binding energy of your crystal. kind regards -- Dr. Lorenzo Paulatto IdR @ IMPMC -- CNRS & Universit? Paris 6 +33 (0)1 44 275 084 / skype: paulatz http://www-int.impmc.upmc.fr/~paulatto/ 23-24/4?16 Bo?te courrier 115, 4 place Jussieu 75252 Paris C?dex 05 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20140205/ed47a1df/attachment.html -------------- next part -------------- A non-text attachment was scrubbed... Name: smime.p7s Type: application/pkcs7-signature Size: 2956 bytes Desc: S/MIME Cryptographic Signature Url : http://pwscf.org/pipermail/pw_forum/attachments/20140205/ed47a1df/attachment.bin
