From owner-chemistry@ccl.net Fri Mar 25 08:41:01 2016 From: "Elliot S. MENKAH elliotsmenkah.(0).hotmail.com" To: CCL Subject: CCL: Fiorentini-Methefessel: Surface energy Message-Id: <-52121-160325082351-13742-JuMsLzIQO7kCrmgHFaxzNA(0)server.ccl.net> X-Original-From: "Elliot S. MENKAH" Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" Date: Fri, 25 Mar 2016 12:16:20 +0000 MIME-Version: 1.0 Sent to CCL by: "Elliot S. MENKAH" [elliotsmenkah||hotmail.com] Hello Everyone, In reference to the paper Extracting convergent surface energies from slab calculations, 1996, 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: esmenkah[#]knust.edu.gh elliotsmenkah[#]gmail.com elliotsmenkah[#]yahoo.com webpage: http://chemistry.knust.edu.gh/MMC/group-members/ESMenkah From owner-chemistry@ccl.net Fri Mar 25 11:35:01 2016 From: "Michael Sluydts michael.sluydts],[ugent.be" To: CCL Subject: CCL: Fiorentini-Methefessel: Surface energy Message-Id: <-52122-160325113124-22637-anyacX30wX9BVcu1ODuwWA^^^server.ccl.net> X-Original-From: Michael Sluydts Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=utf-8; format=flowed Date: Fri, 25 Mar 2016 16:31:02 +0100 MIME-Version: 1.0 Sent to CCL by: Michael Sluydts [michael.sluydts:+:ugent.be] Hello Elliot, While not a direct answer to your question, keep in mind that for the typical bulk cell calculation you can nowadays use so many k-points that the error becomes sufficiently negligible to be as good as fancier techniques such as the one you are using there. We've checked this in our current research and I think this was concluded in the following article as well: Nicholas E. Singh-Miller and Nicola Marzari, "Surface energies, work functions, and surface relaxations of low-index metallic surfaces from rst principles," Physical Review B, vol. 80, no. 23, pp. 235407, Dec. 2009. Best regards, Michael On 3/25/2016 1:16 PM, Elliot S. MENKAH elliotsmenkah.]^[.hotmail.com wrote: > Sent to CCL by: "Elliot S. MENKAH" [elliotsmenkah||hotmail.com] > Hello Everyone, > > In reference to the paper Extracting convergent surface energies from slab calculations, 1996, 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. > > -- ir. Michael Sluydts Center for Molecular Modeling Ghent University Technologiepark 903 9052 Zwijnaarde, Belgium tel. +32 (0)9 264 66 19 https://molmod.ugent.be