#[cfg(test)]
mod test;
use crate::{
math::{Scalar, Tensor, random_uniform, random_x2_normal},
mechanics::CurrentCoordinate,
physics::{
BOLTZMANN_CONSTANT,
molecular::single_chain::{
Configuration, Ensemble, Extensible, Isometric, Isotensional, Legendre, MonteCarlo,
SingleChain, SingleChainError, Thermodynamics,
},
},
};
use std::f64::consts::TAU;
#[derive(Clone, Debug)]
pub struct ExtensibleFreelyRotatingChain {
pub link_angle: Scalar,
pub link_length: Scalar,
pub link_stiffness: Scalar,
pub number_of_links: u8,
pub ensemble: Ensemble,
}
impl ExtensibleFreelyRotatingChain {
fn nondimensional_link_stiffness(&self) -> Scalar {
self.link_stiffness * self.link_length().powi(2) / BOLTZMANN_CONSTANT / self.temperature()
}
}
impl SingleChain for ExtensibleFreelyRotatingChain {
fn link_length(&self) -> Scalar {
self.link_length
}
fn number_of_links(&self) -> u8 {
self.number_of_links
}
}
impl Extensible for ExtensibleFreelyRotatingChain {}
impl Thermodynamics for ExtensibleFreelyRotatingChain {
fn ensemble(&self) -> Ensemble {
self.ensemble
}
}
impl Isometric for ExtensibleFreelyRotatingChain {
fn nondimensional_helmholtz_free_energy(
&self,
_nondimensional_extension: Scalar,
) -> Result<Scalar, SingleChainError> {
unimplemented!()
}
fn nondimensional_force(
&self,
_nondimensional_extension: Scalar,
) -> Result<Scalar, SingleChainError> {
unimplemented!()
}
fn nondimensional_stiffness(
&self,
_nondimensional_extension: Scalar,
) -> Result<Scalar, SingleChainError> {
unimplemented!()
}
fn nondimensional_spherical_distribution(
&self,
_nondimensional_extension: Scalar,
) -> Result<Scalar, SingleChainError> {
unimplemented!()
}
}
impl Isotensional for ExtensibleFreelyRotatingChain {
fn nondimensional_gibbs_free_energy_per_link(
&self,
_nondimensional_force: Scalar,
) -> Result<Scalar, SingleChainError> {
unimplemented!()
}
fn nondimensional_extension(
&self,
_nondimensional_force: Scalar,
) -> Result<Scalar, SingleChainError> {
unimplemented!()
}
fn nondimensional_compliance(
&self,
_nondimensional_force: Scalar,
) -> Result<Scalar, SingleChainError> {
unimplemented!()
}
}
impl Legendre for ExtensibleFreelyRotatingChain {
fn nondimensional_spherical_distribution(
&self,
_nondimensional_extension: Scalar,
) -> Result<Scalar, SingleChainError> {
unimplemented!()
}
}
impl MonteCarlo for ExtensibleFreelyRotatingChain {
fn random_nondimensional_link_vectors(&self, nondimensional_force: Scalar) -> Configuration {
if nondimensional_force != 0.0 {
todo!()
}
let std = 1.0 / self.nondimensional_link_stiffness().sqrt();
let cos_theta = 2.0 * random_uniform() - 1.0;
let sin_theta = (1.0 - cos_theta * cos_theta).sqrt();
let phi = TAU * random_uniform();
let (sin_phi, cos_phi) = phi.sin_cos();
const AY: CurrentCoordinate = CurrentCoordinate::const_from([0.0, 1.0, 0.0]);
const AZ: CurrentCoordinate = CurrentCoordinate::const_from([0.0, 0.0, 1.0]);
let mut a = AY;
let mut b =
CurrentCoordinate::const_from([sin_theta * cos_phi, sin_theta * sin_phi, cos_theta]);
let (sin_theta, cos_theta) = self.link_angle.sin_cos();
(0..self.number_of_links())
.map(|link| {
if link > 0 {
a = if b[1].abs() < 0.9 { AY } else { AZ };
let u = a.cross(&b).normalized();
let v = b.cross(&u);
let phi = TAU * random_uniform();
let (sin_phi, cos_phi) = phi.sin_cos();
b = &b * cos_theta + (&u * cos_phi + &v * sin_phi) * sin_theta;
}
&b * random_x2_normal(1.0, std)
})
.collect()
}
}