Struct PointCharge 

pub struct PointCharge {
    pub atomic_number: u8,
    pub position: [f64; 3],
    pub charge: f64,
}

A point charge source external to the QEq system.

This struct represents an atom from the environment (e.g., a protein residue) that contributes a fixed electrostatic potential to the QEq system but does not participate in charge redistribution. Unlike QEq atoms, these charges remain constant throughout the calculation.

Fields

atomic_number: u8

The atomic number of the external atom, used to retrieve screening parameters.

This allows the solver to compute screened Coulomb integrals using the same STO/GTO formalism as internal atoms, ensuring physical consistency at short distances.

position: [f64; 3]

The 3D position of the external charge in Cartesian coordinates (Ångströms).

charge: f64

The fixed partial charge assigned to this atom (elementary charge units).

This value typically comes from a classical force field (e.g., AMBER, CHARMM) and remains constant throughout the QEq calculation.

Implementations

impl PointCharge

pub fn new(atomic_number: u8, position: [f64; 3], charge: f64) -> Self

Creates a new point charge with the specified parameters.

Arguments

• atomic_number - The atomic number of the element.
• position - The 3D Cartesian coordinates in Ångströms.
• charge - The fixed partial charge in elementary charge units.

Returns

A new PointCharge instance.

Examples

use cheq::PointCharge;

let oxygen = PointCharge::new(8, [1.234, 5.678, 9.012], -0.5679);

Trait Implementations

impl Clone for PointCharge

fn clone(&self) -> PointCharge

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PointCharge

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

Formats the value using the given formatter.

impl PartialEq for PointCharge

fn eq(&self, other: &PointCharge) -> 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 Copy for PointCharge

impl StructuralPartialEq for PointCharge