The State Point

The file src/state_point.rs defines a struct that holds the signac state point. The template executes a Lennard-Jones fluid simulation. The state point sets the number of beads, the potential parameters, the temperature (in units of energy), the number density, and the replicate index.

use serde::{Deserialize, Serialize};

/// Model parameters that describe a single simulation.
#[derive(Serialize, Deserialize)]
pub struct StatePoint {
    pub n: usize,
    pub epsilon: f64,
    pub sigma: f64,
    pub temperature: f64,
    pub number_density: f64,
    pub replicate: u32,
}

Signac stores these state points in JSON files in the workspace directory. To populate that directory with three example state points, execute:

$ python populate_workspace.py

You might be wondering what the #[derive(Serialize, Deserialize)] is for. In simulate.rs (explained later), the workflow reads the state point using serde_json:

let state_point_bytes = fs::read("signac_statepoint.json")?;
let state_point: StatePoint = serde_json::from_slice(&state_point_bytes)?;

#[derive(Serialize, Deserialize)] invokes a macro that automatically implements the Serialize and Deserialize traits for our type.

Tip

To implement your own simulation model, replace the struct fields with ones that match your state point.