exercises:2017_ethz_mmm:mc_and_kmc
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| exercises:2017_ethz_mmm:mc_and_kmc [2017/03/08 15:47] – dpasserone | exercises:2017_ethz_mmm:mc_and_kmc [2020/08/21 10:15] (current) – external edit 127.0.0.1 | ||
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| - | ====== | + | ====== |
| ===== | ===== | ||
| In this exercise you will perform a MC simulation for different coverages of " | In this exercise you will perform a MC simulation for different coverages of " | ||
| Line 7: | Line 7: | ||
| <note tip> | <note tip> | ||
| - | All files of this exercise be downloaded from the wiki: {{e3_bis.zip|}} | + | All files of this exercise |
| Download the exercise into your $HOME folder and unzip it. | Download the exercise into your $HOME folder and unzip it. | ||
| < | < | ||
| - | you@eulerX ~$ wget http:// | + | you@eulerX ~$ wget http:// |
| - | you@eulerX ~$ unzip exercises: | + | you@eulerX ~$ unzip exercises: |
| you@eulerX ~$ cd exercise_3 | you@eulerX ~$ cd exercise_3 | ||
| </ | </ | ||
| Line 20: | Line 20: | ||
| In an experiment performed at Empa, sumanene molecules were adsorbed on a Ag(111) surface. | In an experiment performed at Empa, sumanene molecules were adsorbed on a Ag(111) surface. | ||
| It was found that at very low coverage (0.02) 30% of the molecules were weakly bound into dimers. | It was found that at very low coverage (0.02) 30% of the molecules were weakly bound into dimers. | ||
| + | [ [[http:// | ||
| - | IMAGE | + | {{: |
| <note tip> | <note tip> | ||
| Line 27: | Line 28: | ||
| (blue dots) are allowed to move by random discrete steps | (blue dots) are allowed to move by random discrete steps | ||
| - | IMAGE LATTICE | + | {{: |
| While in execution, the code will show you snapshots of the positions of the molecules on the lattice | While in execution, the code will show you snapshots of the positions of the molecules on the lattice | ||
| on the left panel. | on the left panel. | ||
| + | |||
| + | {{: | ||
| + | |||
| In the central panel average values for the number of isolated molecules, the number of dimers and the number of clusters | In the central panel average values for the number of isolated molecules, the number of dimers and the number of clusters | ||
| is plotted. | is plotted. | ||
| Line 55: | Line 59: | ||
| where k is Boltzmann' | where k is Boltzmann' | ||
| T is the simulation (and experiment) temperature | T is the simulation (and experiment) temperature | ||
| - | n0 is teh concentration of dimers in the case of zero interaction | + | n0 is the concentration of dimers in the case of zero interaction |
| nexp is the concentration of dimers found in the experiment | nexp is the concentration of dimers found in the experiment | ||
| + | To compute the concentration consider that at coverage 0.02, in the simulation, the total number of molecules is 50 | ||
| </ | </ | ||
| Line 74: | Line 79: | ||
| < | < | ||
| - | #### MAIN MC LOOP | + | clusters_plot=[] |
| + | for i in range(nouter): | ||
| and also the section | and also the section | ||
| Line 99: | Line 105: | ||
| </ | </ | ||
| which finds out all the molecules that are 1st neighbors to a given one. | which finds out all the molecules that are 1st neighbors to a given one. | ||
| - | Th efunction | + | |
| + | The function | ||
| you imagine roughly a more efficient function to perform the same task? | you imagine roughly a more efficient function to perform the same task? | ||
| + | </ | ||
| + | <note warning> | ||
| + | The code, at each step, moves a particle chosen randomly to a new site chosen randomly. | ||
| + | **Would it be correct to move all particles in a step? | ||
| + | what would change?** | ||
| </ | </ | ||
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