exercises:2018_ethz_mmm:lennard_jones_cluster_2018
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exercises:2018_ethz_mmm:lennard_jones_cluster_2018 [2018/02/22 14:33] โ dpasserone | exercises:2018_ethz_mmm:lennard_jones_cluster_2018 [2018/02/23 08:48] โ dpasserone | ||
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+ | <note tip> | ||
+ | All files of this exercise be downloaded directly from the wiki: {{exercise_1.1.zip|}} | ||
+ | </ | ||
+ | |||
+ | Download the 1.1 exercise into your **EXERCISES** folder and unzip it. | ||
+ | |||
+ | < | ||
+ | max@qmobile: | ||
+ | max@qmobile: | ||
+ | max@qmobile: | ||
+ | max@qmobile: | ||
+ | </ | ||
+ | |||
+ | |||
+ | |||
+ | In this exercise you will test the Lennard-Jones potential. In particular, we will focus on the system described in the following paper about the energy landscape of the 38 atom Lennard-Jones cluster: | ||
+ | <note tip>{{ : | ||
+ | </ | ||
+ | |||
+ | The command to run cp2k is the following (with a generic **file.inp** input file): | ||
< | < | ||
max@qmobile: | max@qmobile: | ||
</ | </ | ||
+ | |||
+ | |||
+ | ===== Geometry optimization | ||
+ | In this first part you will perform a simple energy optimization, | ||
+ | |||
+ | The input file structure of the template is the following: | ||
+ | |||
+ | <code - geo_opt.inp> | ||
+ | &GLOBAL | ||
+ | | ||
+ | | ||
+ | | ||
+ | | ||
+ | | ||
+ | &END GLOBAL | ||
+ | |||
+ | &MOTION | ||
+ | & | ||
+ | OPTIMIZER BFGS | ||
+ | MAX_ITER | ||
+ | MAX_DR | ||
+ | RMS_DR | ||
+ | MAX_FORCE 0.0001 | ||
+ | RMS_FORCE 0.00003 | ||
+ | &BFGS | ||
+ | | ||
+ | &END BFGS | ||
+ | & | ||
+ | & | ||
+ | & | ||
+ | | ||
+ | & | ||
+ | GEO_OPT 1 | ||
+ | & | ||
+ | &END TRAJECTORY | ||
+ | & | ||
+ | &END MOTION | ||
+ | |||
+ | & | ||
+ | | ||
+ | | ||
+ | & | ||
+ | & | ||
+ | &CHARGE | ||
+ | ATOM Ar | ||
+ | CHARGE 0.0 | ||
+ | &END | ||
+ | & | ||
+ | & | ||
+ | atoms Ar Ar | ||
+ | EPSILON 119.8 | ||
+ | SIGMA 3.405 | ||
+ | RCUT 8.4 | ||
+ | &END LENNARD-JONES | ||
+ | &END NONBONDED | ||
+ | &CHARGE | ||
+ | ATOM Kr | ||
+ | CHARGE 0.0 | ||
+ | &END CHARGE | ||
+ | &END FORCEFIELD | ||
+ | & | ||
+ | | ||
+ | & | ||
+ | EWALD_TYPE none | ||
+ | & | ||
+ | &END POISSON | ||
+ | |||
+ | & | ||
+ | SPLINE_DATA | ||
+ | SPLINE_INFO | ||
+ | & | ||
+ | &END PRINT | ||
+ | & | ||
+ | & | ||
+ | &FORCES off | ||
+ | &END FORCES | ||
+ | & | ||
+ | &END GRID_INFORMATION | ||
+ | & | ||
+ | & | ||
+ | GEO_OPT 1 | ||
+ | & | ||
+ | &END PROGRAM_RUN_INFO | ||
+ | & | ||
+ | & | ||
+ | GEO_OPT 1 | ||
+ | & | ||
+ | &END STRESS_TENSOR | ||
+ | & | ||
+ | & | ||
+ | &CELL | ||
+ | | ||
+ | | ||
+ | | ||
+ | | ||
+ | &END CELL | ||
+ | & | ||
+ | COORD_FILE_NAME in.xyz | ||
+ | COORDINATE xyz | ||
+ | &END | ||
+ | |||
+ | & | ||
+ | & | ||
+ | & | ||
+ | & | ||
+ | & | ||
+ | & | ||
+ | & | ||
+ | & | ||
+ | &END PRINT | ||
+ | & | ||
+ | &END FORCE_EVAL | ||
+ | | ||
+ | </ | ||
+ | <note important> | ||
+ | **1 Hartree=27.2114 eV**. | ||
+ | In the input file, the epsilon value (depth of the well) is expressed in KT units, namely, in " | ||
+ | </ | ||
+ | <note tip> | ||
+ | - randomize the coordinate files **fcc.xyz** (which represents the " | ||
+ | - extract the q4 order parameter from **fcc.xyz** and from **fcc_rand.xyz** and compare the values. | ||
+ | - < | ||
+ | - before running the simulation, copy the input coordinate file into in.xyz < | ||
+ | - Before running cp2k, check if the file **OPT-pos-1.xyz** is already present from a previous run. In that case remove or delete it accordingly. It contains the trajectory of the optimization. | ||
+ | - run cp2k < | ||
+ | - in the output file, grep the final energy < | ||
+ | - Open vmd and play with the optimization trajectory < | ||
+ | - apply the script **myq4** to the optimization trajectory: this generates a list of q4 and energies for the whole trajectory. < | ||
+ | - plot q4 and energies with **gnuplot** (ask the teacher) | ||
+ | - have a look at the myq4 script < | ||
+ | - repeat for the ico.xyz starting point, don't forget to first copy/remove the files appropriately. For example: < | ||
+ | - Run the bash script < | ||
+ | - create a FCC_OUT subdirectory (**mkdir FCC_OUT ; cd FCC_OUT**) and copy there the files you want to keep; then go back one dir (**cd ..**), delete all the OPT* files (**rm OPT* **) and repeat the exercise with ico.xyz | ||
+ | |||
+ | </ | ||
+ | |||
+ | |||
+ | |||
+ | |||
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<note tip> | <note tip> | ||
- Report the energy of the minima, compare it with the ones of the initial configurations. | - Report the energy of the minima, compare it with the ones of the initial configurations. | ||
+ | - After converting the energy into " | ||
- Plot q4 vs. energy and q4 vs. optimization steps, for the two cases. Discuss the results. Are the minima in two separate basins? | - Plot q4 vs. energy and q4 vs. optimization steps, for the two cases. Discuss the results. Are the minima in two separate basins? | ||
- Report the value of the order parameter of the minumum, and discuss what you see | - Report the value of the order parameter of the minumum, and discuss what you see | ||
- Use " | - Use " | ||
</ | </ | ||
- | --> | + |
exercises/2018_ethz_mmm/lennard_jones_cluster_2018.txt ยท Last modified: 2020/08/21 10:15 by 127.0.0.1