exercises:2014_ethz_mmm:surface_cu

# Surface energies of Copper high-symmetry surfaces

In this exercise we will compute the surface energies of Cu using the EAM potential. As a reference, we report the table from the Gross book:

- Copy the files from from the wiki: exercise_3.1.zip (
**all inputs are commented**) into a new directory - Use the batch
**run_cp2k_lattice**to run a chain of simulations on a Cu bulk system. From the output**lat.out**check the lattice constant corresponding to minimum cohesive energy**PER ATOM**(divide by the number of particles, find it out!), you will need it later - Run the optimizations 100.inp, 110.inp, 111.inp —- look at the corresponding initial coordinate files 100.xyz, 110.xyz, 111.xyz.
- In vmd, you can also open a console, and give the command
**pbc set { a b c 90 90 90 }**where a, b, c can be extracted from the cp2k input file. Then you can make several periodic copies for visualization. - Compute the three surface energies: you need to compute the area, subtract bulk contribution, take care of the units.
- In the class we will learn how to compute the Wulff crystal from these three numbers.
- Basically, you should edit the input file “DP”, replacing the column beginning with
**“PUT_HERE_THE_XXX_SURFACE_ENERGY”**with quantities that are proportional to the three surface free energies (see Wulff theorem). Note that for the {100} and {110} surfaces you need to edit**TWO**lines each, since the**z**direction is treated differently in this program. - At this point, you run the program with the command
**./sowos.v02.00.02.x** - There will be many output files. Important are
- * the atomistic model
**out.atomistic-inside-gnuplot.xyz**which will contain many atoms if you chose a proportionality constant in the file DP which is too large. If you appropriately modify it (how?) you can have a xyz file to be opened in vmd. - * the
**out.plot-gnuplot.plt**file. If you launch gnuplot, then “**load “out.plot-gnuplot.plt”**a plot of the crystal will be shown. To have it more or less to scale in all directions:**set xrange [-80:80];set yrange [-80:80]; set view equal xyz; replot** - * you can rotate with the mouse!

**Assignment: use the cluster generated with SOWOS as an input configuration for a cluster optimization with cp2k. Comment on the final geometry. BEWARE OF THE CELL! It is not a periodic system!**

documentation on

**SOWOS**can be found at the web site of Daniele Scopeceexercises/2014_ethz_mmm/surface_cu.txt · Last modified: 2020/08/21 10:15 by 127.0.0.1