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exercises:2014_ethz_mmm:monte_carlo_ice

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exercise:monte_carlo_ice [2014/05/23 14:00] – oschuettexercises:2014_ethz_mmm:monte_carlo_ice [2020/08/21 10:15] (current) – external edit 127.0.0.1
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 ====== Properties of Ice from Monte Carlo Simulations ====== ====== Properties of Ice from Monte Carlo Simulations ======
 +<note important>
 +  - Add the line ''PRINT_COORDS .FALSE.'' in the ''TMC'' section. It disables the output of the coordinate trajectory and thus avoids the files-size problem.
 +  - Add the line ''RND_DETERMINISTIC 42'' to the ''TMC'' section to choose a random number seed. You have to replace ''42'' with different values to obtain different samplings.
 +</note>
 +
 In this exercise we will use Monte Carlo sampling to calculate the [[wp>Relative_permittivity|dielectric constant]] and the [[wp>Thermal_expansion#Coefficient_of_thermal_expansion| thermal expansion coefficient]] of the disordered hexagonal phase (Ih) of water ice. In order to speed up the calculation we are going to use the simple SPC/E water model. For more information see: [[doi>10.1063/1.1568337]]. A DFT-version of the calculation can be found here: [[doi>10.1021/jp4103355]]. In this exercise we will use Monte Carlo sampling to calculate the [[wp>Relative_permittivity|dielectric constant]] and the [[wp>Thermal_expansion#Coefficient_of_thermal_expansion| thermal expansion coefficient]] of the disordered hexagonal phase (Ih) of water ice. In order to speed up the calculation we are going to use the simple SPC/E water model. For more information see: [[doi>10.1063/1.1568337]]. A DFT-version of the calculation can be found here: [[doi>10.1021/jp4103355]].
  
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 ===== Task 2: Gather more samplings ===== ===== Task 2: Gather more samplings =====
-You can gather more samples by launching multiple independent runs in parallel. The python-script can process multiple trajectories:+You can gather more samples by launching multiple independent runs in parallel with different random number seeds. The seed is given by the ''RND_DETERMINISTIC'' keyword. The gathered trajectories can then be analyzed collectively with the python-script:
 <code> <code>
 you@brutusX ~$ ./calc_dielectric_constant.py 200 trj_1_T200.00.dip_cl trj_1_T200.00.dip_cl ... you@brutusX ~$ ./calc_dielectric_constant.py 200 trj_1_T200.00.dip_cl trj_1_T200.00.dip_cl ...
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 ===== Required Files ===== ===== Required Files =====
 ==== Initial Coordinates ==== ==== Initial Coordinates ====
-{{:exercise:ice_ih_96.xyz.gz| Download here}}+{{ice_ih_96.xyz.gz| Download here}}
  
  
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   RUN_TYPE TMC   RUN_TYPE TMC
   PRINT_LEVEL LOW   PRINT_LEVEL LOW
-  WALLTIME 2:00:00+  WALLTIME 1:00:00
 &END GLOBAL &END GLOBAL
 &MOTION &MOTION
   &TMC   &TMC
 +      RND_DETERMINISTIC 42 !<=== Change this number to obtain different samplings
 +      PRINT_COORDS .FALSE. !this avoids the file-size problem
       GROUP_CC_SIZE 0       GROUP_CC_SIZE 0
       NUM_MC_ELEM 100000       NUM_MC_ELEM 100000
exercises/2014_ethz_mmm/monte_carlo_ice.1400853639.txt.gz · Last modified: 2020/08/21 10:14 (external edit)