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CustomGBForce Class Reference

This class implements complex, multiple stage nonbonded interactions between particles. More...

`#include <CustomGBForce.h>`

Inheritance diagram for CustomGBForce:

## Public Types

enum | NonbondedMethod { NoCutoff = 0, CutoffNonPeriodic = 1, CutoffPeriodic = 2 }
| This is an enumeration of the different methods that may be used for handling long range nonbonded forces. More...
enum | ComputationType { SingleParticle = 0, ParticlePair = 1, ParticlePairNoExclusions = 2 }
| This is an enumeration of the different ways in which a computed value or energy term can be calculated. More...

## Public Member Functions

| CustomGBForce ()
| Create a CustomGBForce. More...
| ~CustomGBForce ()
int | getNumParticles () const
| Get the number of particles for which force field parameters have been defined. More...
int | getNumExclusions () const
| Get the number of particle pairs whose interactions should be excluded. More...
int | getNumPerParticleParameters () const
| Get the number of per-particle parameters that the interaction depends on. More...
int | getNumGlobalParameters () const
| Get the number of global parameters that the interaction depends on. More...
int | getNumTabulatedFunctions () const
| Get the number of tabulated functions that have been defined. More...
int | getNumFunctions () const
| Get the number of tabulated functions that have been defined. More...
int | getNumComputedValues () const
| Get the number of per-particle computed values the interaction depends on. More...
int | getNumEnergyTerms () const
| Get the number of terms in the energy computation. More...
NonbondedMethod | getNonbondedMethod () const
| Get the method used for handling long range nonbonded interactions. More...
void | setNonbondedMethod (NonbondedMethod method)
| Set the method used for handling long range nonbonded interactions. More...
double | getCutoffDistance () const
| Get the cutoff distance (in nm) being used for nonbonded interactions. More...
void | setCutoffDistance (double distance)
| Set the cutoff distance (in nm) being used for nonbonded interactions. More...
int | addPerParticleParameter (const std::string &name)
| Add a new per-particle parameter that the interaction may depend on. More...
const std::string & | getPerParticleParameterName (int index) const
| Get the name of a per-particle parameter. More...
void | setPerParticleParameterName (int index, const std::string &name)
| Set the name of a per-particle parameter. More...
int | addGlobalParameter (const std::string &name, double defaultValue)
| Add a new global parameter that the interaction may depend on. More...
const std::string & | getGlobalParameterName (int index) const
| Get the name of a global parameter. More...
void | setGlobalParameterName (int index, const std::string &name)
| Set the name of a global parameter. More...
double | getGlobalParameterDefaultValue (int index) const
| Get the default value of a global parameter. More...
void | setGlobalParameterDefaultValue (int index, double defaultValue)
| Set the default value of a global parameter. More...
int | addParticle (const std::vector< double > &parameters)
| Add the nonbonded force parameters for a particle. More...
void | getParticleParameters (int index, std::vector< double > &parameters) const
| Get the nonbonded force parameters for a particle. More...
void | setParticleParameters (int index, const std::vector< double > &parameters)
| Set the nonbonded force parameters for a particle. More...
int | addComputedValue (const std::string &name, const std::string &expression, ComputationType type)
| Add a computed value to calculate for each particle. More...
void | getComputedValueParameters (int index, std::string &name, std::string &expression, ComputationType &type) const
| Get the properties of a computed value. More...
void | setComputedValueParameters (int index, const std::string &name, const std::string &expression, ComputationType type)
| Set the properties of a computed value. More...
int | addEnergyTerm (const std::string &expression, ComputationType type)
| Add a term to the energy computation. More...
void | getEnergyTermParameters (int index, std::string &expression, ComputationType &type) const
| Get the properties of a term to the energy computation. More...
void | setEnergyTermParameters (int index, const std::string &expression, ComputationType type)
| Set the properties of a term to the energy computation. More...
int | addExclusion (int particle1, int particle2)
| Add a particle pair to the list of interactions that should be excluded. More...
void | getExclusionParticles (int index, int &particle1, int &particle2) const
| Get the particles in a pair whose interaction should be excluded. More...
void | setExclusionParticles (int index, int particle1, int particle2)
| Set the particles in a pair whose interaction should be excluded. More...
int | addTabulatedFunction (const std::string &name, TabulatedFunction *function)
| Add a tabulated function that may appear in expressions. More...
const TabulatedFunction & | getTabulatedFunction (int index) const
| Get a const reference to a tabulated function that may appear in expressions. More...
TabulatedFunction & | getTabulatedFunction (int index)
| Get a reference to a tabulated function that may appear in expressions. More...
const std::string & | getTabulatedFunctionName (int index) const
| Get the name of a tabulated function that may appear in expressions. More...
int | addFunction (const std::string &name, const std::vector< double > &values, double min, double max)
| Add a tabulated function that may appear in expressions. More...
void | getFunctionParameters (int index, std::string &name, std::vector< double > &values, double &min, double &max) const
| Get the parameters for a tabulated function that may appear in expressions. More...
void | setFunctionParameters (int index, const std::string &name, const std::vector< double > &values, double min, double max)
| Set the parameters for a tabulated function that may appear in expressions. More...
void | updateParametersInContext (Context &context)
| Update the per-particle parameters in a Context to match those stored in this Force object. More...
bool | usesPeriodicBoundaryConditions () const
| Returns whether or not this force makes use of periodic boundary conditions. More...
Public Member Functions inherited from Force
| Force ()
virtual | ~Force ()
int | getForceGroup () const
| Get the force group this Force belongs to. More...
void | setForceGroup (int group)
| Set the force group this Force belongs to. More...

## Protected Member Functions

ForceImpl * | createImpl () const
| When a Context is created, it invokes this method on each Force in the System. More...
Protected Member Functions inherited from Force
ForceImpl & | getImplInContext (Context &context)
| Get the ForceImpl corresponding to this Force in a Context. More...
ContextImpl & | getContextImpl (Context &context)
| Get the ContextImpl corresponding to a Context. More...

## Detailed Description

This class implements complex, multiple stage nonbonded interactions between particles.

It is designed primarily for implementing Generalized Born implicit solvation models, although it is not strictly limited to that purpose. The interaction is specified as a series of computations, each defined by an arbitrary algebraic expression. It also allows tabulated functions to be defined and used with the computations. It optionally supports periodic boundary conditions and cutoffs for long range interactions.

The computation consists of calculating some number of per-particle computed values, followed by one or more energy terms. A computed value is a scalar value that is computed for each particle in the system. It may depend on an arbitrary set of global and per-particle parameters, and well as on other computed values that have been calculated before it. Once all computed values have been calculated, the energy terms and their derivatives are evaluated to determine the system energy and particle forces. The energy terms may depend on global parameters, per-particle parameters, and per-particle computed values.

When specifying a computed value or energy term, you provide an algebraic expression to evaluate and a computation type describing how the expression is to be evaluated. There are two main types of computations:

- Single Particle: The expression is evaluated once for each particle in the System. In the case of a computed value, this means the value for a particle depends only on other properties of that particle (its position, parameters, and other computed values). In the case of an energy term, it means each particle makes an independent contribution to the System energy.
- Particle Pairs: The expression is evaluated for every pair of particles in the system. In the case of a computed value, the value for a particular particle is calculated by pairing it with every other particle in the system, evaluating the expression for each pair, and summing them. For an energy term, each particle pair makes an independent contribution to the System energy. (Note that energy terms are assumed to be symmetric with respect to the two interacting particles, and therefore are evaluated only once per pair. In contrast, expressions for computed values need not be symmetric and therefore are calculated twice for each pair: once when calculating the value for the first particle, and again when calculating the value for the second particle.)

Be aware that, although this class is extremely general in the computations it can define, particular Platforms may only support more restricted types of computations. In particular, all currently existing Platforms require that the first computed value must be a particle pair computation, and all computed values after the first must be single particle computations. This is sufficient for most Generalized Born models, but might not permit some other types of calculations to be implemented.

This is a complicated class to use, and an example may help to clarify it. The following code implements the OBC variant of the GB/SA solvation model, using the ACE approximation to estimate surface area:

``

    CustomGBForce* custom = new CustomGBForce();
    custom->addPerParticleParameter("q");
    custom->addPerParticleParameter("radius");
    custom->addPerParticleParameter("scale");
    custom->addGlobalParameter("solventDielectric", obc->getSolventDielectric());
    custom->addGlobalParameter("soluteDielectric", obc->getSoluteDielectric());
    custom->addComputedValue("I", "step(r+sr2-or1)*0.5*(1/L-1/U+0.25*(1/U^2-1/L^2)*(r-sr2*sr2/r)+0.5*log(L/U)/r+C);"
                                  "U=r+sr2;"
                                  "C=2*(1/or1-1/L)*step(sr2-r-or1);"
                                  "L=max(or1, D);"
                                  "D=abs(r-sr2);"
                                  "sr2 = scale2*or2;"
                                  "or1 = radius1-0.009; or2 = radius2-0.009", CustomGBForce::ParticlePairNoExclusions);
    custom->addComputedValue("B", "1/(1/or-tanh(1*psi-0.8*psi^2+4.85*psi^3)/radius);"
                                  "psi=I*or; or=radius-0.009", CustomGBForce::SingleParticle);
    custom->addEnergyTerm("28.3919551*(radius+0.14)^2*(radius/B)^6-0.5*138.935456*(1/soluteDielectric-1/solventDielectric)*q^2/B",
                          CustomGBForce::SingleParticle);
    custom->addEnergyTerm("-138.935456*(1/soluteDielectric-1/solventDielectric)*q1*q2/f;"
                          "f=sqrt(r^2+B1*B2*exp(-r^2/(4*B1*B2)))", CustomGBForce::ParticlePair);

It begins by defining three per-particle parameters (charge, atomic radius, and scale factor) and two global parameters (the dielectric constants for the solute and solvent). It then defines a computed value "I" of type ParticlePair. The expression for evaluating it is a complicated function of the distance between each pair of particles (r), their atomic radii (radius1 and radius2), and their scale factors (scale1 and scale2). Very roughly speaking, it is a measure of the distance between each particle and other nearby particles.

Next a computation is defined for the Born Radius (B). It is computed independently for each particle, and is a function of that particle's atomic radius and the intermediate value I defined above.

Finally, two energy terms are defined. The first one is computed for each particle and represents the surface area term, as well as the self interaction part of the polarization energy. The second term is calculated for each pair of particles, and represents the screening of electrostatic interactions by the solvent.

After defining the force as shown above, you should then call addParticle() once for each particle in the System to set the values of its per-particle parameters (q, radius, and scale). The number of particles for which you set parameters must be exactly equal to the number of particles in the System, or else an exception will be thrown when you try to create a Context. After a particle has been added, you can modify its parameters by calling setParticleParameters(). This will have no effect on Contexts that already exist unless you call updateParametersInContext().

CustomGBForce also lets you specify "exclusions", particular pairs of particles whose interactions should be omitted from calculations. This is most often used for particles that are bonded to each other. Even if you specify exclusions, however, you can use the computation type ParticlePairNoExclusions to indicate that exclusions should not be applied to a particular piece of the computation.

Expressions may involve the operators + (add), - (subtract), * (multiply), / (divide), and ^ (power), and the following functions: sqrt, exp, log, sin, cos, sec, csc, tan, cot, asin, acos, atan, sinh, cosh, tanh, erf, erfc, min, max, abs, floor, ceil, step, delta, select. All trigonometric functions are defined in radians, and log is the natural logarithm. step(x) = 0 if x is less than 0, 1 otherwise. delta(x) = 1 if x is 0, 0 otherwise. select(x,y,z) = z if x = 0, y otherwise. In expressions for particle pair calculations, the names of per-particle parameters and computed values have the suffix "1" or "2" appended to them to indicate the values for the two interacting particles. As seen in the above example, an expression may also involve intermediate quantities that are defined following the main expression, using ";" as a separator.

In addition, you can call addTabulatedFunction() to define a new function based on tabulated values. You specify the function by creating a TabulatedFunction object. That function can then appear in expressions.

## Member Enumeration Documentation

enum ComputationType

This is an enumeration of the different ways in which a computed value or energy term can be calculated.

Enumerator
SingleParticle | The value is computed independently for each particle, based only on the parameters and computed values for that particle.
ParticlePair | The value is computed as a sum over all pairs of particles, except those which have been added as exclusions.
ParticlePairNoExclusions | The value is computed as a sum over all pairs of particles. Unlike ParticlePair, the list of exclusions is ignored and all pairs are included in the sum, even those marked as exclusions.

enum NonbondedMethod

This is an enumeration of the different methods that may be used for handling long range nonbonded forces.

Enumerator
NoCutoff | No cutoff is applied to nonbonded interactions. The full set of N^2 interactions is computed exactly. This necessarily means that periodic boundary conditions cannot be used. This is the default.
CutoffNonPeriodic | Interactions beyond the cutoff distance are ignored.
CutoffPeriodic | Periodic boundary conditions are used, so that each particle interacts only with the nearest periodic copy of each other particle. Interactions beyond the cutoff distance are ignored.

## Constructor & Destructor Documentation

CustomGBForce | ( |  | ) |

Create a CustomGBForce.

~CustomGBForce | ( |  | ) |

## Member Function Documentation

int addComputedValue | ( | const std::string & | name,
|  | const std::string & | expression,
|  | ComputationType | type
| ) |  |

Add a computed value to calculate for each particle.

Parameters

  name | the name of the value

  expression

  an algebraic expression to evaluate when calculating the computed value. If the ComputationType is SingleParticle, the expression is evaluated independently for each particle, and may depend on its x, y, and z coordinates, as well as the per-particle parameters and previous computed values for that particle. If the ComputationType is ParticlePair or ParticlePairNoExclusions, the expression is evaluated once for every other particle in the system and summed to get the final value. In the latter case, the expression may depend on the distance r between the two particles, and on the per-particle parameters and previous computed values for each of them. Append "1" to a variable name to indicate the parameter for the particle whose value is being calculated, and "2" to indicate the particle it is interacting with.

  type | the method to use for computing this value

int addEnergyTerm | ( | const std::string & | expression,
|  | ComputationType | type
| ) |  |

Add a term to the energy computation.

Parameters

  expression

  an algebraic expression to evaluate when calculating the energy. If the ComputationType is SingleParticle, the expression is evaluated once for each particle, and may depend on its x, y, and z coordinates, as well as the per-particle parameters and computed values for that particle. If the ComputationType is ParticlePair or ParticlePairNoExclusions, the expression is evaluated once for every pair of particles in the system. In the latter case, the expression may depend on the distance r between the two particles, and on the per-particle parameters and computed values for each of them. Append "1" to a variable name to indicate the parameter for the first particle in the pair and "2" to indicate the second particle in the pair.

  type | the method to use for computing this value

int addExclusion | ( | int | particle1,
|  | int | particle2
| ) |  |

Add a particle pair to the list of interactions that should be excluded.

Parameters

  particle1 | the index of the first particle in the pair
  particle2 | the index of the second particle in the pair

Returns
  the index of the exclusion that was added

int addFunction | ( | const std::string & | name,
|  | const std::vector< double > & | values,
|  | double | min,
|  | double | max
| ) |  |

Add a tabulated function that may appear in expressions.

Deprecated:
  This method exists only for backward compatibility. Use addTabulatedFunction() instead.

int addGlobalParameter | ( | const std::string & | name,
|  | double | defaultValue
| ) |  |

Add a new global parameter that the interaction may depend on.

Parameters

  name | the name of the parameter
  defaultValue | the default value of the parameter

Returns
  the index of the parameter that was added

int addParticle | ( | const std::vector< double > & | parameters | ) |

Add the nonbonded force parameters for a particle.

This should be called once for each particle in the System. When it is called for the i'th time, it specifies the parameters for the i'th particle.

Parameters

  parameters | the list of parameters for the new particle

Returns
  the index of the particle that was added

int addPerParticleParameter | ( | const std::string & | name | ) |

Add a new per-particle parameter that the interaction may depend on.

Parameters

  name | the name of the parameter

Returns
  the index of the parameter that was added

int addTabulatedFunction | ( | const std::string & | name,
|  | TabulatedFunction * | function
| ) |  |

Add a tabulated function that may appear in expressions.

Parameters

  name | the name of the function as it appears in expressions
  function | a TabulatedFunction object defining the function. The TabulatedFunction should have been created on the heap with the "new" operator. The Force takes over ownership of it, and deletes it when the Force itself is deleted.

Returns
  the index of the function that was added

ForceImpl* createImpl | ( |  | ) | const

protectedvirtual

When a Context is created, it invokes this method on each Force in the System.

It should create a new ForceImpl object which can be used by the context for calculating forces. The ForceImpl will be deleted automatically when the Context is deleted.

Implements Force.

void getComputedValueParameters | ( | int | index,
|  | std::string & | name,
|  | std::string & | expression,
|  | ComputationType & | type
| ) |  | const

Get the properties of a computed value.

Parameters

  index | the index of the computed value for which to get parameters
  name | the name of the value

  expression

  an algebraic expression to evaluate when calculating the computed value. If the ComputationType is SingleParticle, the expression is evaluated independently for each particle, and may depend on its x, y, and z coordinates, as well as the per-particle parameters and previous computed values for that particle. If the ComputationType is ParticlePair or ParticlePairNoExclusions, the expression is evaluated once for every other particle in the system and summed to get the final value. In the latter case, the expression may depend on the distance r between the two particles, and on the per-particle parameters and previous computed values for each of them. Append "1" to a variable name to indicate the parameter for the particle whose value is being calculated, and "2" to indicate the particle it is interacting with.

  type | the method to use for computing this value

double getCutoffDistance | ( |  | ) | const

Get the cutoff distance (in nm) being used for nonbonded interactions.

If the NonbondedMethod in use is NoCutoff, this value will have no effect.

Returns
  the cutoff distance, measured in nm

void getEnergyTermParameters | ( | int | index,
|  | std::string & | expression,
|  | ComputationType & | type
| ) |  | const

Get the properties of a term to the energy computation.

Parameters

  index | the index of the term for which to get parameters

  expression

  an algebraic expression to evaluate when calculating the energy. If the ComputationType is SingleParticle, the expression is evaluated once for each particle, and may depend on its x, y, and z coordinates, as well as the per-particle parameters and computed values for that particle. If the ComputationType is ParticlePair or ParticlePairNoExclusions, the expression is evaluated once for every pair of particles in the system. In the latter case, the expression may depend on the distance r between the two particles, and on the per-particle parameters and computed values for each of them. Append "1" to a variable name to indicate the parameter for the first particle in the pair and "2" to indicate the second particle in the pair.

  type | the method to use for computing this value

void getExclusionParticles | ( | int | index,
|  | int & | particle1,
|  | int & | particle2
| ) |  | const

Get the particles in a pair whose interaction should be excluded.

Parameters

  index | the index of the exclusion for which to get particle indices
  particle1 | the index of the first particle in the pair
  particle2 | the index of the second particle in the pair

void getFunctionParameters | ( | int | index,
|  | std::string & | name,
|  | std::vector< double > & | values,
|  | double & | min,
|  | double & | max
| ) |  | const

Get the parameters for a tabulated function that may appear in expressions.

Deprecated:
  This method exists only for backward compatibility. Use getTabulatedFunctionParameters() instead. If the specified function is not a Continuous1DFunction, this throws an exception.

double getGlobalParameterDefaultValue | ( | int | index | ) | const

Get the default value of a global parameter.

Parameters

  index | the index of the parameter for which to get the default value

Returns
  the parameter default value

const std::string& getGlobalParameterName | ( | int | index | ) | const

Get the name of a global parameter.

Parameters

  index | the index of the parameter for which to get the name

Returns
  the parameter name

NonbondedMethod getNonbondedMethod | ( |  | ) | const

Get the method used for handling long range nonbonded interactions.

int getNumComputedValues | ( |  | ) | const

inline

Get the number of per-particle computed values the interaction depends on.

int getNumEnergyTerms | ( |  | ) | const

inline

Get the number of terms in the energy computation.

int getNumExclusions | ( |  | ) | const

inline

Get the number of particle pairs whose interactions should be excluded.

int getNumFunctions | ( |  | ) | const

inline

Get the number of tabulated functions that have been defined.

Deprecated:
  This method exists only for backward compatibility. Use getNumTabulatedFunctions() instead.

int getNumGlobalParameters | ( |  | ) | const

inline

Get the number of global parameters that the interaction depends on.

int getNumParticles | ( |  | ) | const

inline

Get the number of particles for which force field parameters have been defined.

int getNumPerParticleParameters | ( |  | ) | const

inline

Get the number of per-particle parameters that the interaction depends on.

int getNumTabulatedFunctions | ( |  | ) | const

inline

Get the number of tabulated functions that have been defined.

void getParticleParameters | ( | int | index,
|  | std::vector< double > & | parameters
| ) |  | const

Get the nonbonded force parameters for a particle.

Parameters

  index | the index of the particle for which to get parameters
  parameters | the list of parameters for the specified particle

const std::string& getPerParticleParameterName | ( | int | index | ) | const

Get the name of a per-particle parameter.

Parameters

  index | the index of the parameter for which to get the name

Returns
  the parameter name

const TabulatedFunction& getTabulatedFunction | ( | int | index | ) | const

Get a const reference to a tabulated function that may appear in expressions.

Parameters

  index | the index of the function to get

Returns
  the TabulatedFunction object defining the function

TabulatedFunction& getTabulatedFunction | ( | int | index | ) |

Get a reference to a tabulated function that may appear in expressions.

Parameters

  index | the index of the function to get

Returns
  the TabulatedFunction object defining the function

const std::string& getTabulatedFunctionName | ( | int | index | ) | const

Get the name of a tabulated function that may appear in expressions.

Parameters

  index | the index of the function to get

Returns
  the name of the function as it appears in expressions

void setComputedValueParameters | ( | int | index,
|  | const std::string & | name,
|  | const std::string & | expression,
|  | ComputationType | type
| ) |  |

Set the properties of a computed value.

Parameters

  index | the index of the computed value for which to set parameters
  name | the name of the value

  expression

  an algebraic expression to evaluate when calculating the computed value. If the ComputationType is SingleParticle, the expression is evaluated independently for each particle, and may depend on its x, y, and z coordinates, as well as the per-particle parameters and previous computed values for that particle. If the ComputationType is ParticlePair or ParticlePairNoExclusions, the expression is evaluated once for every other particle in the system and summed to get the final value. In the latter case, the expression may depend on the distance r between the two particles, and on the per-particle parameters and previous computed values for each of them. Append "1" to a variable name to indicate the parameter for the particle whose value is being calculated, and "2" to indicate the particle it is interacting with.

  type | the method to use for computing this value

void setCutoffDistance | ( | double | distance | ) |

Set the cutoff distance (in nm) being used for nonbonded interactions.

If the NonbondedMethod in use is NoCutoff, this value will have no effect.

Parameters

  distance | the cutoff distance, measured in nm

void setEnergyTermParameters | ( | int | index,
|  | const std::string & | expression,
|  | ComputationType | type
| ) |  |

Set the properties of a term to the energy computation.

Parameters

  index | the index of the term for which to set parameters

  expression

  an algebraic expression to evaluate when calculating the energy. If the ComputationType is SingleParticle, the expression is evaluated once for each particle, and may depend on its x, y, and z coordinates, as well as the per-particle parameters and computed values for that particle. If the ComputationType is ParticlePair or ParticlePairNoExclusions, the expression is evaluated once for every pair of particles in the system. In the latter case, the expression may depend on the distance r between the two particles, and on the per-particle parameters and computed values for each of them. Append "1" to a variable name to indicate the parameter for the first particle in the pair and "2" to indicate the second particle in the pair.

  type | the method to use for computing this value

void setExclusionParticles | ( | int | index,
|  | int | particle1,
|  | int | particle2
| ) |  |

Set the particles in a pair whose interaction should be excluded.

Parameters

  index | the index of the exclusion for which to set particle indices
  particle1 | the index of the first particle in the pair
  particle2 | the index of the second particle in the pair

void setFunctionParameters | ( | int | index,
|  | const std::string & | name,
|  | const std::vector< double > & | values,
|  | double | min,
|  | double | max
| ) |  |

Set the parameters for a tabulated function that may appear in expressions.

Deprecated:
  This method exists only for backward compatibility. Use setTabulatedFunctionParameters() instead. If the specified function is not a Continuous1DFunction, this throws an exception.

void setGlobalParameterDefaultValue | ( | int | index,
|  | double | defaultValue
| ) |  |

Set the default value of a global parameter.

Parameters

  index | the index of the parameter for which to set the default value
  name | the default value of the parameter

void setGlobalParameterName | ( | int | index,
|  | const std::string & | name
| ) |  |

Set the name of a global parameter.

Parameters

  index | the index of the parameter for which to set the name
  name | the name of the parameter

void setNonbondedMethod | ( | NonbondedMethod | method | ) |

Set the method used for handling long range nonbonded interactions.

void setParticleParameters | ( | int | index,
|  | const std::vector< double > & | parameters
| ) |  |

Set the nonbonded force parameters for a particle.

Parameters

  index | the index of the particle for which to set parameters
  parameters | the list of parameters for the specified particle

void setPerParticleParameterName | ( | int | index,
|  | const std::string & | name
| ) |  |

Set the name of a per-particle parameter.

Parameters

  index | the index of the parameter for which to set the name
  name | the name of the parameter

void updateParametersInContext | ( | Context & | context | ) |

Update the per-particle parameters in a Context to match those stored in this Force object.

This method provides an efficient method to update certain parameters in an existing Context without needing to reinitialize it. Simply call setParticleParameters() to modify this object's parameters, then call updateParametersInContext() to copy them over to the Context.

This method has several limitations. The only information it updates is the values of per-particle parameters. All other aspects of the Force (such as the energy function) are unaffected and can only be changed by reinitializing the Context. Also, this method cannot be used to add new particles, only to change the parameters of existing ones.

bool usesPeriodicBoundaryConditions | ( |  | ) | const

inlinevirtual

Returns whether or not this force makes use of periodic boundary conditions.

Returns
  true if force uses PBC and false otherwise

Reimplemented from Force.

References CustomGBForce::CutoffPeriodic.

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

- CustomGBForce.h