PyCGTOOL provides a means to quickly and easily generate coarse-grained molecular dynamics models within the MARTINI framework from all-atom or united-atom simulation trajectories.
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@@ -29,6 +27,11 @@ PyCGTOOL requires:
Optional:
- MDTraj for pseudo-CG XTC output (http://mdtraj.org/1.7.2/) with own dependencies:
- Scipy (https://www.scipy.org/)
- Cython (http://cython.org/)
- Python testing framework (e.g. Nose2, py.test)
- Numba for increased performance (http://numba.pydata.org/)
- Sphinx to generate documentation yourself (http://www.sphinx-doc.org/en/stable/)
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@@ -42,8 +45,8 @@ PyCGTOOL requires four input files to generate a coarse-grained model:
Example mapping and bond definition files are present in the ``test/data`` directory. Their format is explained below.
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@@ -58,8 +61,8 @@ Mapping Definition
~~~~~~~~~~~~~~~~~~
An example of mapping definition file for the monosaccharide allose taken from ``test/data/sugar.map`` is shown below.
Molecule names (as present in the gro coordinate file) are used as section headers inside square brackets. Each of the following lines describes a single coarse-grained bead mapping. The items on a line are: the name of the bead, its MARTINI bead type, a list of all the atom names it should contain. All items on a line are whitespace separated. Multiple molecules may be specified in their own sections. It is not recommended to provide a mapping for water since MARTINI water combines four molecules into a single bead which is not yet supported by PyCGTOOL.
::
Molecule names (as present in the gro coordinate file) are used as section headers inside square brackets. Each of the following lines describes a single coarse-grained bead mapping. The items on a line are: the name of the bead, its MARTINI bead type, a list of all the atom names it should contain. All items on a line are whitespace separated. Multiple molecules may be specified in their own sections. It is not recommended to provide a mapping for water since MARTINI water combines four molecules into a single bead which is not yet supported by PyCGTOOL. ::
; comments begin with a semicolon
[ALLA]
C1 P3 C1 O1
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@@ -78,8 +81,8 @@ An example bond definition file for the monosaccharide allose taken from ``test/
As in the mapping definition file, molecule names are used as section headers inside square brackets. The following lines define bonds lengths, angles and dihedrals between coarse-grained beads. Each line is a list of bead names, using the names defined in the mapping file. Two bead names on a line defines a bond length, three defines an angle, and four defines a dihedral.
If no angles are defined for a molecule, PyCGTOOL will construct all angles from the list of bonds. This may also be enabled for dihedrals via the ``--interactive`` flag, but is not recommended as in most cases coarse-grained models do not require dihedrals. Additionally, any angles inside a triangle of bond lengths are excluded from the output as they often cause simulation stability issues when used in conjunction with LINCS.
::
If no angles are defined for a molecule, PyCGTOOL will construct all angles from the list of bonds. This may also be enabled for dihedrals via the ``--interactive`` flag, but is not recommended as in most cases coarse-grained models do not require dihedrals. Additionally, any angles inside a triangle of bond lengths are excluded from the output as they often cause simulation stability issues when used in conjunction with LINCS. ::
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[ALLA]
C1 C2
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@@ -111,12 +114,12 @@ Modes
~~~~~
PyCGTOOL performs several other functions which may be useful in the testing and use of coarse-grained models.
Mapping-only mode performs a coarse-grain mapping on a single frame and may be used to generate initial coordinates for a coarse-grain simulation, whether the model being used was created by PyCGTOOL or not. In this respect it functions similarly to the MARTINI tool MARTINIZE. This mode may be invoked by:
::
Mapping-only mode performs a coarse-grain mapping on a single frame and may be used to generate initial coordinates for a coarse-grain simulation, whether the model being used was created by PyCGTOOL or not. In this respect it functions similarly to the MARTINI tool MARTINIZE. This mode may be invoked by::
pycgtool.py -g <GRO file> -m <MAP file>
Measure-only mode may be used to aid in the testing of a coarse-grained model by making measurements of bonds from a true corase-grained simulation trajectory. These bond measurements are those collected from the pseudo-coarse-grained trajectory used to generate the model, so are a directly comparable measure of model accuracy. This mode may be invoked by:
::
Measure-only mode may be used to aid in the testing of a coarse-grained model by making measurements of bonds from a true corase-grained simulation trajectory. These bond measurements are those collected from the pseudo-coarse-grained trajectory used to generate the model, so are a directly comparable measure of model accuracy. This mode may be invoked by::