AmoebaMultipoleForce¶
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class
simtk.openmm.openmm.
AmoebaMultipoleForce
(*args)¶ This class implements the Amoeba multipole interaction.
To use it, create an AmoebaMultipoleForce object then call addMultipole() once for each atom. After an entry has been added, you can modify its force field parameters by calling setMultipoleParameters(). This will have no effect on Contexts that already exist unless you call updateParametersInContext().
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__init__
(self) → AmoebaMultipoleForce¶ __init__(self, other) -> AmoebaMultipoleForce
Create an AmoebaMultipoleForce.
Methods
__init__
((self) -> AmoebaMultipoleForce)__init__(self, other) -> AmoebaMultipoleForce addMultipole
((self, charge, molecularDipole, ...)Add multipole-related info for a particle getAEwald
((self) -> double)Get the Ewald alpha parameter. getCovalentMap
(self, index, typeId)Get the CovalentMap for an atom getCovalentMaps
(self, index)Get the CovalentMap for an atom getCutoffDistance
((self) -> double)Get the cutoff distance (in nm) being used for nonbonded interactions. getElectrostaticPotential
(self, inputGrid, ...)Get the electrostatic potential. getEwaldErrorTolerance
((self) -> double)Get the error tolerance for Ewald summation. getExtrapolationCoefficients
((self) -> vectord)Get the coefficients for the mu_0, mu_1, mu_2, ..., mu_n terms in the extrapolation algorithm for induced dipoles. getForceGroup
((self) -> int)Get the force group this Force belongs to. getInducedDipoles
(self, context)Get the induced dipole moments of all particles. getLabFramePermanentDipoles
(self, context)Get the fixed dipole moments of all particles in the global reference frame. getMultipoleParameters
(self, index)Get the multipole parameters for a particle. getMutualInducedMaxIterations
((self) -> int)Get the max number of iterations to be used in calculating the mutual induced dipoles getMutualInducedTargetEpsilon
((self) -> double)Get the target epsilon to be used to test for convergence of iterative method used in calculating the mutual induced dipoles getNonbondedMethod
(...)Get the method used for handling long-range nonbonded interactions. getNumMultipoles
((self) -> int)Get the number of particles in the potential function getPMEParameters
(self)Get the parameters to use for PME calculations. getPMEParametersInContext
(self, context)Get the parameters being used for PME in a particular Context. getPmeBSplineOrder
((self) -> int)Get the B-spline order to use for PME charge spreading getPmeGridDimensions
(self)Get the PME grid dimensions. getPolarizationType
(...)Get polarization type getSystemMultipoleMoments
(self, context)Get the system multipole moments. getTotalDipoles
(self, context)Get the total dipole moments (fixed plus induced) of all particles. setAEwald
(self, aewald)Set the Ewald alpha parameter. setCovalentMap
(self, index, typeId, ...)Set the CovalentMap for an atom setCutoffDistance
(self, distance)Set the cutoff distance (in nm) being used for nonbonded interactions. setEwaldErrorTolerance
(self, tol)Get the error tolerance for Ewald summation. setExtrapolationCoefficients
(self, coefficients)Set the coefficients for the mu_0, mu_1, mu_2, ..., mu_n terms in the extrapolation algorithm for induced dipoles. setForceGroup
(self, group)Set the force group this Force belongs to. setMultipoleParameters
(self, index, charge, ...)Set the multipole parameters for a particle. setMutualInducedMaxIterations
(self, ...)Set the max number of iterations to be used in calculating the mutual induced dipoles setMutualInducedTargetEpsilon
(self, ...)Set the target epsilon to be used to test for convergence of iterative method used in calculating the mutual induced dipoles setNonbondedMethod
(self, method)Set the method used for handling long-range nonbonded interactions. setPMEParameters
(self, alpha, nx, ny, nz)Set the parameters to use for PME calculations. setPmeGridDimensions
(self, gridDimension)Set the PME grid dimensions. setPolarizationType
(self, type)Set the polarization type updateParametersInContext
(self, context)Update the multipole parameters in a Context to match those stored in this Force object. usesPeriodicBoundaryConditions
((self) -> bool)Returns whether or not this force makes use of periodic boundary conditions. Attributes
Bisector
Covalent12
Covalent13
Covalent14
Covalent15
CovalentEnd
Direct
Extrapolated
LastAxisTypeIndex
Mutual
NoAxisType
NoCutoff
PME
PolarizationCovalent11
PolarizationCovalent12
PolarizationCovalent13
PolarizationCovalent14
ThreeFold
ZBisect
ZOnly
ZThenX
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getNumMultipoles
(self) → int¶ Get the number of particles in the potential function
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getNonbondedMethod
(self) → OpenMM::AmoebaMultipoleForce::NonbondedMethod¶ Get the method used for handling long-range nonbonded interactions.
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setNonbondedMethod
(self, method)¶ Set the method used for handling long-range nonbonded interactions.
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getPolarizationType
(self) → OpenMM::AmoebaMultipoleForce::PolarizationType¶ Get polarization type
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setPolarizationType
(self, type)¶ Set the polarization type
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getCutoffDistance
(self) → double¶ 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 Return type: double
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setCutoffDistance
(self, 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 (double) – the cutoff distance, measured in nm
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getPMEParameters
(self)¶ Get the parameters to use for PME calculations. If alpha is 0 (the default), these parameters are ignored and instead their values are chosen based on the Ewald error tolerance.
Returns: - alpha (double) – the separation parameter
- nx (int) – the number of grid points along the X axis
- ny (int) – the number of grid points along the Y axis
- nz (int) – the number of grid points along the Z axis
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setPMEParameters
(self, alpha, nx, ny, nz)¶ Set the parameters to use for PME calculations. If alpha is 0 (the default), these parameters are ignored and instead their values are chosen based on the Ewald error tolerance.
Parameters: - alpha (double) – the separation parameter
- nx (int) – the number of grid points along the X axis
- ny (int) – the number of grid points along the Y axis
- nz (int) – the number of grid points along the Z axis
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getAEwald
(self) → double¶ Get the Ewald alpha parameter. If this is 0 (the default), a value is chosen automatically based on the Ewald error tolerance.
Deprecated
This method exists only for backward compatibility. Use getPMEParameters() instead.
Returns: the Ewald alpha parameter Return type: double
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setAEwald
(self, aewald)¶ Set the Ewald alpha parameter. If this is 0 (the default), a value is chosen automatically based on the Ewald error tolerance.
Deprecated
This method exists only for backward compatibility. Use setPMEParameters() instead.
Parameters: aewald (double) – alpha parameter
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getPmeBSplineOrder
(self) → int¶ Get the B-spline order to use for PME charge spreading
Returns: the B-spline order Return type: int
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getPmeGridDimensions
(self)¶ Get the PME grid dimensions. If Ewald alpha is 0 (the default), this is ignored and grid dimensions are chosen automatically based on the Ewald error tolerance.
Deprecated
This method exists only for backward compatibility. Use getPMEParameters() instead.
Returns: the PME grid dimensions Return type: void
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setPmeGridDimensions
(self, gridDimension)¶ Set the PME grid dimensions. If Ewald alpha is 0 (the default), this is ignored and grid dimensions are chosen automatically based on the Ewald error tolerance.
Deprecated
This method exists only for backward compatibility. Use setPMEParameters() instead.
Parameters: gridDimension (vector< int >) – the PME grid dimensions
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getPMEParametersInContext
(self, context)¶ Get the parameters being used for PME in a particular Context. Because some platforms have restrictions on the allowed grid sizes, the values that are actually used may be slightly different from those specified with setPmeGridDimensions(), or the standard values calculated based on the Ewald error tolerance. See the manual for details.
Parameters: context (Context) – the Context for which to get the parameters Returns: - alpha (double) – the separation parameter
- nx (int) – the number of grid points along the X axis
- ny (int) – the number of grid points along the Y axis
- nz (int) – the number of grid points along the Z axis
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addMultipole
(self, charge, molecularDipole, molecularQuadrupole, axisType, multipoleAtomZ, multipoleAtomX, multipoleAtomY, thole, dampingFactor, polarity) → int¶ Add multipole-related info for a particle
Parameters: - charge (double) – the particle’s charge
- molecularDipole (vector< double >) – the particle’s molecular dipole (vector of size 3)
- molecularQuadrupole (vector< double >) – the particle’s molecular quadrupole (vector of size 9)
- axisType (int) – the particle’s axis type
- multipoleAtomZ (int) – index of first atom used in constructing lab<->molecular frames
- multipoleAtomX (int) – index of second atom used in constructing lab<->molecular frames
- multipoleAtomY (int) – index of second atom used in constructing lab<->molecular frames
- thole (double) – Thole parameter
- dampingFactor (double) – dampingFactor parameter
- polarity (double) – polarity parameter
Returns: the index of the particle that was added
Return type: int
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getMultipoleParameters
(self, index)¶ Get the multipole parameters for a particle.
Parameters: index (int) – the index of the atom for which to get parameters Returns: - charge (double) – the particle’s charge
- molecularDipole (vector< double >) – the particle’s molecular dipole (vector of size 3)
- molecularQuadrupole (vector< double >) – the particle’s molecular quadrupole (vector of size 9)
- axisType (int) – the particle’s axis type
- multipoleAtomZ (int) – index of first atom used in constructing lab<->molecular frames
- multipoleAtomX (int) – index of second atom used in constructing lab<->molecular frames
- multipoleAtomY (int) – index of second atom used in constructing lab<->molecular frames
- thole (double) – Thole parameter
- dampingFactor (double) – dampingFactor parameter
- polarity (double) – polarity parameter
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setMultipoleParameters
(self, index, charge, molecularDipole, molecularQuadrupole, axisType, multipoleAtomZ, multipoleAtomX, multipoleAtomY, thole, dampingFactor, polarity)¶ Set the multipole parameters for a particle.
Parameters: - index (int) – the index of the atom for which to set parameters
- charge (double) – the particle’s charge
- molecularDipole (vector< double >) – the particle’s molecular dipole (vector of size 3)
- molecularQuadrupole (vector< double >) – the particle’s molecular quadrupole (vector of size 9)
- axisType (int) – the particle’s axis type
- multipoleAtomZ (int) – index of first atom used in constructing lab<->molecular frames
- multipoleAtomX (int) – index of second atom used in constructing lab<->molecular frames
- multipoleAtomY (int) – index of second atom used in constructing lab<->molecular frames
- thole (double) – thole parameter
- dampingFactor (double) – damping factor parameter
- polarity (double) – polarity parameter
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setCovalentMap
(self, index, typeId, covalentAtoms)¶ Set the CovalentMap for an atom
Parameters: - index (int) – the index of the atom for which to set parameters
- typeId (CovalentType) – CovalentTypes type
- covalentAtoms (vector< int >) – vector of covalent atoms associated w/ the specfied CovalentType
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getCovalentMap
(self, index, typeId)¶ Get the CovalentMap for an atom
Parameters: - index (int) – the index of the atom for which to set parameters
- typeId (CovalentType) – CovalentTypes type
Returns: covalentAtoms – output vector of covalent atoms associated w/ the specfied CovalentType
Return type: vector< int >
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getCovalentMaps
(self, index)¶ Get the CovalentMap for an atom
Parameters: index (int) – the index of the atom for which to set parameters Returns: covalentLists – output vector of covalent lists of atoms Return type: vector< std::vector< int > >
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getMutualInducedMaxIterations
(self) → int¶ Get the max number of iterations to be used in calculating the mutual induced dipoles
Returns: max number of iterations Return type: int
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setMutualInducedMaxIterations
(self, inputMutualInducedMaxIterations)¶ Set the max number of iterations to be used in calculating the mutual induced dipoles
Parameters: inputMutualInducedMaxIterations (int) – number of iterations
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getMutualInducedTargetEpsilon
(self) → double¶ Get the target epsilon to be used to test for convergence of iterative method used in calculating the mutual induced dipoles
Returns: target epsilon Return type: double
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setMutualInducedTargetEpsilon
(self, inputMutualInducedTargetEpsilon)¶ Set the target epsilon to be used to test for convergence of iterative method used in calculating the mutual induced dipoles
Parameters: inputMutualInducedTargetEpsilon (double) – target epsilon
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setExtrapolationCoefficients
(self, coefficients)¶ Set the coefficients for the mu_0, mu_1, mu_2, ..., mu_n terms in the extrapolation algorithm for induced dipoles.
Parameters: coefficients (vector< double >) – a vector whose mth entry specifies the coefficient for mu_m. The length of this vector determines how many iterations are performed.
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getExtrapolationCoefficients
(self) → vectord¶ Get the coefficients for the mu_0, mu_1, mu_2, ..., mu_n terms in the extrapolation algorithm for induced dipoles. In this release, the default values for the coefficients are [-0.154, 0.017, 0.658, 0.474], but be aware that those may change in a future release.
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getEwaldErrorTolerance
(self) → double¶ Get the error tolerance for Ewald summation. This corresponds to the fractional error in the forces which is acceptable. This value is used to select the grid dimensions and separation (alpha) parameter so that the average error level will be less than the tolerance. There is not a rigorous guarantee that all forces on all atoms will be less than the tolerance, however.
This can be overridden by explicitly setting an alpha parameter and grid dimensions to use.
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setEwaldErrorTolerance
(self, tol)¶ Get the error tolerance for Ewald summation. This corresponds to the fractional error in the forces which is acceptable. This value is used to select the grid dimensions and separation (alpha) parameter so that the average error level will be less than the tolerance. There is not a rigorous guarantee that all forces on all atoms will be less than the tolerance, however.
This can be overridden by explicitly setting an alpha parameter and grid dimensions to use.
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getLabFramePermanentDipoles
(self, context)¶ Get the fixed dipole moments of all particles in the global reference frame.
Parameters: context (Context) – the Context for which to get the fixed dipoles Returns: dipoles – the fixed dipole moment of particle i is stored into the i’th element Return type: vector< Vec3 >
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getInducedDipoles
(self, context)¶ Get the induced dipole moments of all particles.
Parameters: context (Context) – the Context for which to get the induced dipoles Returns: dipoles – the induced dipole moment of particle i is stored into the i’th element Return type: vector< Vec3 >
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getTotalDipoles
(self, context)¶ Get the total dipole moments (fixed plus induced) of all particles.
Parameters: context (Context) – the Context for which to get the total dipoles Returns: dipoles – the total dipole moment of particle i is stored into the i’th element Return type: vector< Vec3 >
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getElectrostaticPotential
(self, inputGrid, context)¶ Get the electrostatic potential.
Parameters: - inputGrid (vector< Vec3 >) – input grid points over which the potential is to be evaluated
- context (Context) – context
Returns: outputElectrostaticPotential – output potential
Return type: vector< double >
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getSystemMultipoleMoments
(self, context)¶ Get the system multipole moments.
This method is most useful for non-periodic systems. When called for a periodic system, only the <i>lowest nonvanishing moment</i> has a well defined value. This means that if the system has a net nonzero charge, the dipole and quadrupole moments are not well defined and should be ignored. If the net charge is zero, the dipole moment is well defined (and really represents a dipole density), but the quadrupole moment is still undefined and should be ignored.
Parameters: context (Context) – context Returns: outputMultipoleMoments – (charge, dipole_x, dipole_y, dipole_z, quadrupole_xx, quadrupole_xy, quadrupole_xz, quadrupole_yx, quadrupole_yy, quadrupole_yz, quadrupole_zx, quadrupole_zy, quadrupole_zz) Return type: vector< double >
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updateParametersInContext
(self, context)¶ Update the multipole 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 setMultipoleParameters() 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 parameters of multipoles. All other aspects of the Force (the nonbonded method, the cutoff distance, etc.) are unaffected and can only be changed by reinitializing the Context. Furthermore, this method cannot be used to add new multipoles, only to change the parameters of existing ones.
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usesPeriodicBoundaryConditions
(self) → bool¶ Returns whether or not this force makes use of periodic boundary conditions.
Returns: true if nonbondedMethod uses PBC and false otherwise Return type: bool
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__copy__
(self) → Force¶
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getForceGroup
(self) → int¶ Get the force group this Force belongs to.
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setForceGroup
(self, group)¶ Set the force group this Force belongs to.
Parameters: group (int) – the group index. Legal values are between 0 and 31 (inclusive).
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