Struct ExternalPotential 

pub struct ExternalPotential { /* private fields */ }

An external electrostatic potential acting on the QEq system.

This struct describes the electrostatic environment surrounding a molecular fragment undergoing charge equilibration. It enables hybrid QEq/MM calculations where the QEq subsystem (e.g., a ligand) responds to the electrostatic field generated by the environment (e.g., a protein binding pocket) without including the environment atoms in the expensive matrix diagonalization.

Implementations

impl ExternalPotential

pub fn new() -> Self

Creates an empty external potential with no contributions.

This is equivalent to computing QEq in vacuum (the default behavior).

Examples

use cheq::ExternalPotential;

let empty = ExternalPotential::new();
assert!(empty.is_empty());

pub fn from_point_charges(charges: Vec<PointCharge>) -> Self

Creates an external potential from a collection of point charges.

Arguments

• charges - A vector of PointCharge representing external atoms.

Returns

A new ExternalPotential instance containing the specified point charges.

Examples

use cheq::{ExternalPotential, PointCharge};

let charges = vec![
    PointCharge::new(8, [3.0, 0.0, 0.0], -0.82),
    PointCharge::new(1, [3.5, 0.7, 0.0],  0.41),
];

let external = ExternalPotential::from_point_charges(charges);
assert_eq!(external.point_charges().len(), 2);

pub fn from_uniform_field(field: [f64; 3]) -> Self

Creates an external potential from a uniform electric field.

Arguments

• field - The electric field vector [Ex, Ey, Ez] in V/Å.

Returns

A new ExternalPotential instance with the specified uniform field.

Examples

use cheq::ExternalPotential;

// Apply a field of 0.1 V/Å along the z-axis (e.g., transmembrane potential)
let external = ExternalPotential::from_uniform_field([0.0, 0.0, 0.1]);

pub fn with_point_charges(self, charges: Vec<PointCharge>) -> Self

Sets the point charges for this external potential.

This method consumes and returns self, enabling a builder-style API.

Arguments

• charges - A vector of PointCharge representing external atoms.

Examples

use cheq::{ExternalPotential, PointCharge};

let external = ExternalPotential::new()
    .with_point_charges(vec![
        PointCharge::new(6, [0.0, 0.0, 5.0], 0.1),
    ])
    .with_uniform_field([0.0, 0.0, 0.05]);

pub fn with_uniform_field(self, field: [f64; 3]) -> Self

Sets the uniform electric field for this external potential.

This method consumes and returns self, enabling a builder-style API.

Arguments

• field - The electric field vector [Ex, Ey, Ez] in V/Å.

Examples

use cheq::ExternalPotential;

let external = ExternalPotential::new()
    .with_uniform_field([0.0, 0.0, 0.2]);

pub fn point_charges(&self) -> &[PointCharge]

Returns a reference to the point charges.

pub fn uniform_field(&self) -> [f64; 3]

Returns the uniform electric field vector.

pub fn is_empty(&self) -> bool

Returns true if this external potential has no contributions.

An empty potential is equivalent to vacuum conditions and will not affect the QEq calculation.

pub fn num_point_charges(&self) -> usize

Returns the total number of point charges.

Trait Implementations

impl Clone for ExternalPotential

fn clone(&self) -> ExternalPotential

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ExternalPotential

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

Formats the value using the given formatter.

impl Default for ExternalPotential

fn default() -> ExternalPotential

Returns the “default value” for a type.

impl PartialEq for ExternalPotential

fn eq(&self, other: &ExternalPotential) -> 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 StructuralPartialEq for ExternalPotential