Struct Lj 

pub struct Lj<T> { /* private fields */ }

Lennard-Jones 12-6 potential.

Parameters

• epsilon: Well depth (energy)
• sigma: Zero-crossing distance (length)

Precomputed Values

Internally stores:

• c6 = 4 * epsilon * sigma^6
• c12 = 4 * epsilon * sigma^12

This allows the potential to be computed as: V = c12/r^12 - c6/r^6

Implementations

impl<T: Vector> Lj<T>

pub fn new(epsilon: f64, sigma: f64) -> Self

Creates a new Lennard-Jones potential from epsilon and sigma.

Arguments

• epsilon: Well depth (energy units)
• sigma: Zero-crossing distance (length units)

Example

use potentials::pair::Lj;

// Argon: epsilon = 0.238 kcal/mol, sigma = 3.4 A
let lj: Lj<f64> = Lj::new(0.238, 3.4);

pub fn from_coefficients(c12: f64, c6: f64) -> Self

Creates a new Lennard-Jones potential from precomputed coefficients.

Arguments

• c12: Coefficient for r^-12 term (4 * epsilon * sigma^12)
• c6: Coefficient for r^-6 term (4 * epsilon * sigma^6)

This is useful when mixing rules produce c6/c12 directly.

pub fn c12(&self) -> T

Returns the c12 coefficient.

pub fn c6(&self) -> T

Returns the c6 coefficient.

Trait Implementations

impl<T: Clone> Clone for Lj<T>

fn clone(&self) -> Lj<T>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for Lj<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: PartialEq> PartialEq for Lj<T>

fn eq(&self, other: &Lj<T>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T: Vector> Potential2<T> for Lj<T>

fn energy(&self, r_sq: T) -> T

Computes the potential energy.

V(r) = c12/r^12 - c6/r^6

fn force_factor(&self, r_sq: T) -> T

Computes the force factor.

dV/dr = -12*c12/r^13 + 6*c6/r^7
S = -(dV/dr)/r = 12*c12/r^14 - 6*c6/r^8
  = 6 * (2*c12/r^12 - c6/r^6) / r^2

fn energy_force(&self, r_sq: T) -> (T, T)

Computes energy and force factor together (optimized).

Shares the computation of r^-6 and r^-12.

impl<T: Copy> Copy for Lj<T>

impl<T> StructuralPartialEq for Lj<T>