Dear Elliot,
I am not sure if I understood correctly your description, but basically:
You plot the energy per layer as a function of the inverse of number of
layers, so starting from the definition
E_surf = [ E_slab(N) - N * E_bulk ] / ( 2 A ) ,
where
Esurf = surface energy per unit area A - sometimes one plots the surface
energy per unit cell; 2 because the slab has two surfaces,
E_slab(N) = total energy of the slab of N layers
E_bulk = the "unknown" bulk energy
Rewriting à la Fiorentini et Methfessel,
E_slab(N)/N = 2A (1/N) E_surf + E_bulk
which is equivalent of an equation
y = 2A E_surf x + E_bulk ^= a x + b
where E_surf and E_bulk are the unknowns, obtained from the fit. So how do
you find E_bulk from this equation (hint: What happens when N ->
infinity?)? And what does the slope yield?
Greetings from Paris,
apsi
-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
Ari Paavo Seitsonen / [email protected] / http://www.iki.fi/~apsi/
Ecole Normale Supérieure (ENS), Département de Chimie, Paris
Mobile (F) : +33 789 37 24 25 (CH) : +41 79 71 90 935
On Fri, 25 Mar 2016, Elliot S. MENKAH wrote:
Hello Everyone,
In reference to the papers Extracting convergent surface energies from slab
calculations, 1996, and Surface e
nergies, work functions, and surface relaxations of low index metallic surfaces
from first-principles, 2009,
I'm trying to compute surface energies with the Fiorentini-Methefessel technique.
I'm extracting the bulk energy from a linear plot of total energy vrs N.
I computed the total energies of nickel surface (100) with 12, 14, 16,
18 and 20 atomic layers.
I made a plot of total energies vrs N(Number of layers) and i got the
equation y = 0.24897 - 171.79x
With the slope being -171.79, am I right to say the bulk energy is
-171.79Ry?
Is this the right way of going about the Fiorentini-Methfessel technique?
Can someone please point me in the right direction
Thank you.
Kind Regards,
Elliot.
--
Elliot Sarpong Menkah
Graduate Student - Computational Chemistry / Computational Material Science.
Theoretical and Computational Chemistry
Dept. of Chemistry
Kwame Nkrumah University of Science and Technology (KNUST),
Private Mail Bag,
Kumasi,
Ghana.
Mobile:+233-243-055-717,+233-202-929-058
Alt. Email: [email protected]
[email protected]
[email protected]
webpage: http://chemistry.knust.edu.gh/MMC/group-members/ESMenkah
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