The view

Per second: Steps: 0


Energy (E) n/a <E> n/a
Density (ρ) n/a <ρ> n/a
Density (ρ1) n/a 1> n/a
Density (ρ2) n/a 2> n/a
Density (ρ3) n/a 3> n/a
Density (ρ4) n/a 4> n/a


Shapes Two-body Interactions

Choose the molecule shapes and colours.

Enter the interaction energies for adjacent shapes for the various colour and edge combinations. The relationship are symmetrical so only one value per pair is required. Negative energies are attractive, positive ones repulsive. Interactions where a spike abuts another spike or flat edge aren't allowed. Two flat edges in contact contribute no additional energy.

Adjacent PairEnergyAdjacent edgesEnergy
Group set:

Choose a shape for molecule x


The buttons below the animation are:

ResetClears the molecules from the container and lets the simulation restart from empty.
ResumeApplies any changes in the "strps" input box and restarts the simulation.
PauseApplies any changes in the "strps" input box and restarts the simulation.
Introductory Video…Takes you to a YoutTbe video showing how to use the application.
Instructions…You must have clicked this to be seeing this page.

The input box labelled "Per second" controls how many iterations per second the simulation will execute. This is a target, if you make this value too large the animation will slow down, it is aiming for 10 updates per second. My PC can manage at least 100,000.

The "Shapes" table has three columns:

MoleculeShows the shape and colour of the molecules, these can be changed using the controls in the other columns.
ColourA drop down list of colours to choose from.
ShapeClick the button to display a list of supported shapes. Click on the one you want.

The "Interactions" table has a number of controls:

Energy(Column 2) Allows you to edit the interaction energy of the pair of molecules in the "Adjacent pair" column. Negative energies are make the molecules attractive, positive energies make them repulsive. Effects are more noticeable when the energy is larger than the temperature.
Energy(Column 4) Allows you to edit the interaction energy of the adornments on the molecule edges. Three of these are hard coded, there is no energy associated with two flat edges and the cases where the spikes intersect the other molecule are forbidden. The others are adjustable in the same way as the "Adjacent pairs"
TemperatureIncreasing the temperature makes the inter-molecular interactions less important and the system bucomes more liquid or gas like.
PressureIncreasing the pressure increases the equilibrium density.
ApplyApplies any changes you have made to the above values.
Group setChanges multiple adjacent pair energies in one go. The input box is the new energy, the buttons perform the following actions:
  • "All": Update all pairwise energies,
  • "All self": Update all energies between two of the same molecules,
  • "All other": Update all energies between two different molecules.


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(c) John Whitehouse 2021