MPCDAnalysis.PairPotentials.WeeksChandlerAndersen_DistanceOffset.WeeksChandlerAndersen_DistanceOffset Class Reference

Public Member Functions
def	__init__ (self, epsilon, sigma, d)
def	getEpsilon (self)
def	getSigma (self)
def	getD (self)
def	getPotential (self, r)

Detailed Description

A generalization of the Weeks-Chandler-Andersen (WCA) potential.

The Weeks-Chandler-Andersen potential has been introduced by Weeks,
Chandler, and Andersen, in J. Chem. Phys. 54, 5237 (1971).
DOI: 10.1063/1.1674820

This generalization introduces an offset \f$ D \f$ of the particle distance
\f$ r \f$. With \f$ \epsilon \f$ and \f$ sigma \f$ being parameters, the
interaction potential is given by
\f[
    4 * \epsilon *
    \left(
        \left( \frac{ \sigma }{ r - D } \right)^{12}
        -
        \left( \frac{ \sigma }{ r - D } \right)^{6}
        +
        \frac{ 1 }{ 4 }
    \right)
    *
    \theta \left( 2^{1/6} \sigma - r + D \right)
\f]
with \f$ \theta \left( x \right) \f$ being the Heaviside step function,
which is \f$ 1 \f$ if \f$ x > 0 \f$, and \f$ 0 \f$ otherwise.

Definition at line 27 of file WeeksChandlerAndersen_DistanceOffset.py.

Constructor & Destructor Documentation

__init__()

def MPCDAnalysis.PairPotentials.WeeksChandlerAndersen_DistanceOffset.WeeksChandlerAndersen_DistanceOffset.__init__	(		self,
			epsilon,
			sigma,
			d
	)

    The constructor.

    @throw TypeError
           Throws if `epsilon`, `sigma`, or `d` are neither `int` nor
           `float`.
    @throw ValueError
           Throws if `epsilon`, `sigma`, or `d` are negative.

    @param[in] epsilon
               The \f$ \epsilon \f$ potential parameter, which must be
               non-negative.
    @param[in] sigma
               The \f$ \sigma \f$ potential parameter, which must be
               non-negative.
    @param[in] d
               The \f$ D \f$ potential parameter, which must be
               non-negative.

Definition at line 49 of file WeeksChandlerAndersen_DistanceOffset.py.

Member Function Documentation

getD()

def MPCDAnalysis.PairPotentials.WeeksChandlerAndersen_DistanceOffset.WeeksChandlerAndersen_DistanceOffset.getD

(

self

)

    Returns the \f$ D \f$ potential parameter as a `float`.

Definition at line 84 of file WeeksChandlerAndersen_DistanceOffset.py.

getEpsilon()

def MPCDAnalysis.PairPotentials.WeeksChandlerAndersen_DistanceOffset.WeeksChandlerAndersen_DistanceOffset.getEpsilon

(

self

)

    Returns the \f$ \epsilon \f$ potential parameter as a `float`.

Definition at line 66 of file WeeksChandlerAndersen_DistanceOffset.py.

getPotential()

def MPCDAnalysis.PairPotentials.WeeksChandlerAndersen_DistanceOffset.WeeksChandlerAndersen_DistanceOffset.getPotential	(		self,
			r
	)

    Returns the potential for an input value of \f$ r \f$.

    @throw TypeError
           Throws if `r` is neither `int` nor `float` or `Vector3DReal`.
    @throw ValueError
           Throws if `r` is negative.
    @throw ValueError
           Throws if `r` is smaller than or equal to \f$ D \f$.

    @param[in] r
               The input value. It may be either an `int` or `float`, in
               which case it must be non-negative. Alternatively, it may be
               of type `Vector3DReal`, which is then euqivalent to calling
               `getPotential(r.getLength())` instead.

Definition at line 106 of file WeeksChandlerAndersen_DistanceOffset.py.

getSigma()

def MPCDAnalysis.PairPotentials.WeeksChandlerAndersen_DistanceOffset.WeeksChandlerAndersen_DistanceOffset.getSigma

(

self

)

    Returns the \f$ \sigma \f$ potential parameter as a `float`.

Definition at line 75 of file WeeksChandlerAndersen_DistanceOffset.py.

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The documentation for this class was generated from the following file:

• WeeksChandlerAndersen_DistanceOffset.py