	This is part of the maze module
	It is only available if you configure PLUMED with ./configure –enable-modules=maze . Furthermore, this feature is still being developed so take care when using it and report any problems on the mailing list.

Calculates the biasing direction along which the ligand unbinds by minimizing the MAZE_LOSS function. The optimal biasing direction is determined by performing a population-based memetics search with local heuristics.

Examples

Every optimizer implemented in the maze module needs a loss function as an argument, and it should be passed using the MAZE_LOSS keyword.

Click on the labels of the actions for more information on what each action computes

ma: MAZE_MEMETIC_SAMPLING ...
   
   LOSSLoss function describing ligand-protein interactions required by every optimizer.
=l 
   N_ITERcompulsory keyword 
Number of optimization steps. =10 
   OPTIMIZER_STRIDEcompulsory keyword 
Optimizer stride. =200 
   CAPACITYcompulsory keyword 
Sampling set size. =20 
   LOCAL_SEARCH_ON( default=off ) Turn local search on.  
   N_LOCAL_ITERNumber of local search iterations. =10 
   LOCAL_SEARCH_RATERate of mutation in local search. =0.1 
   LOCAL_SEARCH_TYPEType of local search. =stochastic_hill_climbing 
   MUTATION_RATEcompulsory keyword 
Probability of mutation. =0.1 
   MATING_RATEcompulsory keyword 
Probability of mating. =0.7 
   CAUCHY_ALPHAcompulsory keyword 
Mean of Cauchy distribution for sampling. =0 
   CAUCHY_BETAcompulsory keyword 
Spread of Cauchy distribution for sampling. =0.1 
   LIGANDIndices of ligand atoms.. =2635-2646 
   PROTEINIndices of protein atoms.. =1-2634 
...The MAZE_MEMETIC_SAMPLING action with label ma calculates the following quantities:

 Quantity    Description  
ma.x Optimal biasing direction; x component.
ma.y Optimal biasing direction; y component.
ma.z Optimal biasing direction; z component.
ma.loss Loss function value defined by the provided pairing function.
ma.sr Sampling radius. Reduces sampling to the local proximity of the ligand position.

As shown above, each optimizer should be provided with the LIGAND and the PROTEIN keywords.

The neighbor list can be turned on by providing the NLIST keyword.

Glossary of keywords and components

Description of components

By default this Action calculates the following quantities. These quantities can be referenced elsewhere in the input by using this Action's label followed by a dot and the name of the quantity required from the list below.

Quantity	Description
x	Optimal biasing direction; x component.
y	Optimal biasing direction; y component.
z	Optimal biasing direction; z component.
loss	Loss function value defined by the provided pairing function.
sr	Sampling radius. Reduces sampling to the local proximity of the ligand position.

The atoms involved can be specified using

LIGAND	Indices of ligand atoms.. For more information on how to specify lists of atoms see Groups and Virtual Atoms
PROTEIN	Indices of protein atoms.. For more information on how to specify lists of atoms see Groups and Virtual Atoms

Compulsory keywords

N_ITER	Number of optimization steps. Required only for optimizers, do not pass this keyword to the fake optimizers (results in crash) , e.g., random walk, steered MD, or random acceleration MD.
OPTIMIZER_STRIDE	Optimizer stride. Sets up a callback function that launches the optimization process every OPTIMIZER_STRIDE.
CAPACITY	Sampling set size.
MUTATION_RATE	Probability of mutation.
MATING_RATE	Probability of mating.
CAUCHY_ALPHA	Mean of Cauchy distribution for sampling.
CAUCHY_BETA	Spread of Cauchy distribution for sampling.

Options

NUMERICAL_DERIVATIVES	( default=off ) calculate the derivatives for these quantities numerically
NOPBC	( default=off ) ignore the periodic boundary conditions when calculating distances
SERIAL	( default=off ) Perform the simulation in serial – used only for debugging purposes, should not be used otherwise.
PAIR	( default=off ) Pair only the 1st element of the 1st group with the 1st element in the second, etc.
NLIST	( default=off ) Use a neighbor list of ligand-protein atom pairs to speed up the calculating of the distances.
LOCAL_SEARCH_ON	( default=off ) Turn local search on.
NL_CUTOFF	Neighbor list cut-off for the distances of ligand-protein atom pairs.
NL_STRIDE	Update stride for the ligand-protein atom pairs in the neighbor list.
LOSS	Loss function describing ligand-protein interactions required by every optimizer.
N_LOCAL_ITER	Number of local search iterations.
LOCAL_SEARCH_RATE	Rate of mutation in local search.
LOCAL_SEARCH_TYPE	Type of local search.

Quantity	Description
ma.x	Optimal biasing direction; x component.
ma.y	Optimal biasing direction; y component.
ma.z	Optimal biasing direction; z component.
ma.loss	Loss function value defined by the provided pairing function.
ma.sr	Sampling radius. Reduces sampling to the local proximity of the ligand position.