Action: SIZESHAPE_POSITION_LINEAR_PROJ
| Module | sizeshape |
|---|---|
| Description | Usage |
| Calculates a linear projection in the space of a given reference configurational distribution in size-and-shape space. | |
| output value | type |
| the linear projection | scalar |
Details and examples
Calculates a linear projection in the space of a given reference configurational distribution in size-and-shape space.
The linear projection is given by:
Where is a vector of linear coefficients, is the configuration at time t, is the difference in the geometric mean of the current configuration and that of the reference configuration . , for N atoms.
is an optimal rotation matrix that minimizes the Mahalanobis distance between the current configuration and reference. is obtained by using Kabsch algorithm within the code. The Mahalanobis distance is given as:
where, is the precision matrix. See also SIZESHAPE_POSITION_MAHA_DIST for information about calculating Mahalanobis distance in size-and-shape space.
Size-and-shape Gaussian Mixture Model (shapeGMM) \cite Heidi-shapeGMM-2022 is a probabilistic clustering technique that is used to perform structural clusteing on ensemble of molecular configurations and to obtain reference and precision corresponding to each of the cluster centers. Please chcek out shapeGMMTorch-GitHub and shapeGMMTorch-PyPI for examples and informations on preforming shapeGMM clustering.
Examples
In the following example, a group is defined with atom indices of selected atoms and then linear projection is calculated for the given reference, precision and coefficients. Each file is a space separated list of 3N floating point numbers.
#SETTINGS INPUTFILES=regtest/sizeshape/rt-sizeshape/global_avg.txt #SETTINGS INPUTFILES=regtest/sizeshape/rt-sizeshape/global_precision.txt #SETTINGS INPUTFILES=regtest/sizeshape/rt-sizeshape/ld1_scalings.txt
UNITSThis command sets the internal units for the code. More details LENGTHthe units of lengths=A TIMEthe units of time=ps ENERGYthe units of energy=kcal/mol GROUPDefine a group of atoms so that a particular list of atoms can be referenced with a single label in definitions of CVs or virtual atoms. More details ATOMSthe numerical indexes for the set of atoms in the group=18,20,22,31,33,35,44,46,48,57,59,61,70,72,74,83,85,87,96,98,100,109,111 LABELa label for the action so that its output can be referenced in the input to other actions=ga_list proj: SIZESHAPE_POSITION_LINEAR_PROJCalculates a linear projection in the space of a given reference configurational distribution in size-and-shape space. More details ... REFERENCECoordinates of the reference structure=regtest/sizeshape/rt-sizeshape/global_avg.txtClick here to see an extract from this file.PRECISIONPrecision Matrix (inverse of covariance)=regtest/sizeshape/rt-sizeshape/global_precision.txtClick here to see an extract from this file.COEFFSVector of linear coefficients=regtest/sizeshape/rt-sizeshape/ld1_scalings.txtClick here to see an extract from this file.GROUPGroup of atoms being used=ga_list ...
PRINTPrint quantities to a file. More details ARGthe labels of the values that you would like to print to the file=proj STRIDE the frequency with which the quantities of interest should be output=1 FILEthe name of the file on which to output these quantities=COLVAR FMT the format that should be used to output real numbers=%8.8f
Input
The atoms that serve as the input for this action are specified using one or more of the keywords in the following table.
| Keyword | Type | Description |
|---|---|---|
| GROUP | atoms | Group of atoms being used |
Full list of keywords
The following table describes the keywords and options that can be used with this action
| Keyword | Type | Default | Description |
|---|---|---|---|
| GROUP | input | none | Group of atoms being used |
| PRECISION | compulsory | none | Precision Matrix (inverse of covariance) |
| REFERENCE | compulsory | none | Coordinates of the reference structure |
| COEFFS | compulsory | none | Vector of linear coefficients |
| NUMERICAL_DERIVATIVESThis keyword do not have examples | optional | false | calculate the derivatives for these quantities numerically |
| NOPBCThis keyword do not have examples | optional | false | ignore the periodic boundary conditions when calculating distances |
| SERIALThis keyword do not have examples | optional | false | Perform the calculation in serial, for debug purposes only |