Expand description
§Angle Bending Potentials
Three-body potentials for bond angle deformation.
§Included Potentials
| Potential | Description | Common Use |
|---|---|---|
Harm | Harmonic k(theta-theta0)^2 | AMBER, OPLS |
Cos | Cosine k(cos-cos0)^2 | GROMOS, DREIDING |
Linear | Linear k(1+cos) | Linear molecules |
Urey | Urey-Bradley (angle + 1-3 bond) | CHARMM |
Cross | Bond-bond cross term | Class II |
§Coordinate Convention
For angle i-j-k:
- j is the central (vertex) atom
- theta is the angle between vectors j->i and j->k
- cos(theta) = (r_ji · r_jk) / (|r_ji| |r_jk|)
§Example
use potentials::angle::{Cos, Potential3};
// Water H-O-H angle: k = 100 kcal/mol, theta0 = 104.5 deg
let theta0_rad = 104.5 * std::f64::consts::PI / 180.0;
let angle = Cos::new(100.0, theta0_rad.cos());
let cos_theta = 0.0; // 90 degrees
let deriv = angle.derivative(1.0, 1.0, cos_theta);Re-exports§
pub use crate::base::Potential3;