NMA Model Editing¶
This module defines functions for editing normal mode data.

extendModel
(model, nodes, atoms, norm=False)[source]¶ Extend a coarse grained model built for nodes to atoms. model may be
ANM
,GNM
,PCA
, orNMA
instance. This function will take part of the normal modes for each node (i.e. Cα atoms) and extend it to all other atoms in the same residue. For each atom in nodes argument atoms argument must contain a corresponding residue. If norm is True, extended modes are normalized.

extendMode
(mode, nodes, atoms, norm=False)[source]¶ Extend a coarse grained normal mode built for nodes to atoms. This function will take part of the normal modes for each node (i.e. Cα atoms) and extend it to all other atoms in the same residue. For each atom in nodes argument atoms argument must contain a corresponding residue. Extended mode is multiplied by the square root of variance of the mode. If norm is True, extended mode is normalized.

extendVector
(vector, nodes, atoms)[source]¶ Extend a coarse grained vector for nodes to atoms. This function will take part of the normal modes for each node (i.e. Cα atoms) and extend it to all other atoms in the same residue. For each atom in nodes, atoms argument must contain a corresponding residue.

sliceMode
(mode, atoms, select)[source]¶ Returns part of the mode for atoms matching select. This works slightly different from
sliceVector()
. Mode array (eigenvector) is multiplied by squareroot of the variance along the mode. If mode is from an elastic network model, variance is defined as the inverse of the eigenvalue. Note that returnedVector
instance is not normalized.Parameters: Returns:

sliceModel
(model, atoms, select)[source]¶ Returns a part of the model for atoms matching select. Note that normal modes (eigenvectors) are not normalized.
Parameters: Returns:

sliceVector
(vector, atoms, select)[source]¶ Returns part of the vector for atoms matching select. Note that returned
Vector
instance is not normalized.Parameters: Returns:

reduceModel
(model, atoms, select)[source]¶ Returns reduced NMA model. Reduces a
NMA
model to a subset of atoms matching select. This function behaves differently depending on the type of the model argument. ForANM
andGNM
or otherNMA
models, force constant matrix for system of interest (specified by the select) is derived from the force constant matrix for the model by assuming that for any given displacement of the system of interest, other atoms move along in such a way as to minimize the potential energy. This is based on the formulation in [KH00]. ForPCA
models, this function simply takes the subcovariance matrix for selection.[KH00] Konrad H, AndreiJose P, Serge D, MarieClaire BF, Gerald RK. Harmonicity in slow protein dynamics. Chem Phys 2000 261:2537. Parameters: Returns: