The metal that I chose to do the calculation for for the first part of lab2 was Cu. The binding energy for the Cu79 truncated octahedron came out as -244.249956 eV. The movie is shown below.
* Update February 24, 2008
I ran a calculation with a Cu shell and a core 19 Iridium atoms. Below is the resluting movie. The binding energy of this structure is -326.49 eV, lower than that of the Cu-only nanoparticle.
I then ran a calculation where I the 19 Ir atom core with a section of 19 Cu atoms on the shell. Posting any more movies on this webpage slows it down significantly, so I will only post the binding energy, which is -321.93 eV, higher than that of the structure with the 19 Ir atoms in the core.
The next step was to run a calculation with an Oxygen atom bonded to a 1,1,1 face on the core-shell atom. The energy of the O bond is equal to the energy of the Cu60Ir19 with Oxygen structure minus the energy of the of Cu60Ir19 by itself minus 1/2 the energy of molecular Oxygen.
Energy of Cu60Ir19O = -324.630538.
Energy of Cu60Ir19 = -335.178483.
Energy of 02 = -8.045784
This is 14.570837 eV. It does not appear that this nanoparticle would act as a very good catalyst for this reaction. The intermediate is at to high of an energy.
Then I ran a calculation of the 60 Cu atoms and the 19 Ir atoms randomly dispersed throughout the structure, which I called Cu60Ir19alloy. It's binding energy was the highest of all of these Cu-Ir structures, at -320.68 eV. It appears that the lowest energy structure I found was the Cu shell with the Ir core.
*Lab 1 I Printed out my journal article and the summary I wrote for it.
When I ran the movie for minimizing of the energy of the cubic Pt32 molecule, the corners of the cube where moved towards the center, as were the sides to a lesser degree. This makes sense, as the a more spherical structure seems like it would be more stable than the cube. The final energy of the Pt32 after the job was run was -150.341144. When taking into consideration that the energy of one Pt atom is -.176408 (from another job), then the binding energy of this Pt32molecule is -144.5926384. It seems logical that the units would be kJ/mol.
When I looked up the cohesive energy for bulk Pt, I foud that it was -5.8 eV. Using a conversion factor, this comes out -219.803 kJ/mol. This is a lower energy structure than the Pt32 that we constructed. This makes sense as there are more atoms for each indiviual atom to interact with and more attractive forces occur in between the atoms in the bulk Pt as opposed to the nanoparticle.I have created my own initla geometry and as of this writing it is still calculating its energy and structure. It has gone through 120 iterations and currently has an energy of -154.487667 kJ/mol. This is not much lower than the energy of the cubic Pt32 molecule, but I expect to get better results as I do more of these types of calculations.
Daniel Tabor dpt252 dannytabor@swbell.net