DensitySphere#
- class maicos.DensitySphere(atomgroups: AtomGroup | List[AtomGroup], dens: str = 'mass', bin_width: float = 1, rmin: float = 0, rmax: float | None = None, refgroup: AtomGroup | None = None, grouping: str = 'atoms', unwrap: bool = True, bin_method: str = 'com', output: str = 'density.dat', concfreq: int = 0, jitter: float = 0.0)[source]#
Bases:
ProfileSphereBase
Spherical partial density profiles.
Calculations are carried out for
mass
\((\rm u \cdot Å^{-3})\),number
\((\rm Å^{-3})\) orcharge
\((\rm e \cdot Å^{-3})\) density profiles along certain cartesian axes[x, y, z]
of the simulation cell. Cell dimensions are allowed to fluctuate in time.For grouping with respect to
molecules
,residues
etc., the corresponding centers (i.e., center of mass), taking into account periodic boundary conditions, are calculated. For these calculations molecules will be unwrapped/made whole. Trajectories containing already whole molecules can be run withunwrap=False
to gain a speedup. For grouping with respect to atoms, the unwrap option is always ignored.For the correlation analysis the 0th bin of the 0th’s group profile is used. For further information on the correlation analysis please refer to
maicos.core.base.AnalysisBase
or the General design section.- Parameters:
atomgroups (MDAnalysis.core.groups.AtomGroup or list[MDAnalysis.core.groups.AtomGroup]) – A
AtomGroup
or list thereof for which the calculations are performed.unwrap (bool) –
When
True
, molecules that are broken due to the periodic boundary conditions are made whole.If the input contains molecules that are already whole, speed up the calculation by disabling unwrap. To do so, use the flag
-no-unwrap
when using MAICoS from the command line, or useunwrap=False
when using MAICoS from the Python interpreter.Note: Molecules containing virtual sites (e.g. TIP4P water models) are not currently supported in MDAnalysis. In this case, you need to provide unwrapped trajectory files directly, and disable unwrap. Trajectories can be unwrapped, for example, using the
trjconv
command of GROMACS.refgroup (MDAnalysis.core.groups.AtomGroup) –
Reference
AtomGroup
used for the calculation.If refgroup is provided, the calculation is performed relative to the center of mass of the AtomGroup.
If refgroup is
None
the calculations are performed to the center of the (changing) box.jitter (float) –
Magnitude of the random noise to add to the atomic positions.
A jitter can be used to stabilize the aliasing effects sometimes appearing when histogramming data. The jitter value should be about the precision of the trajectory. In that case, using jitter will not alter the results of the histogram. If
jitter = 0.0
(default), the original atomic positions are kept unchanged.You can estimate the precision of the positions in your trajectory with
maicos.lib.util.trajectory_precision()
. Note that if the precision is not the same for all frames, the smallest precision should be used.concfreq (int) – When concfreq (for conclude frequency) is larger than 0, the conclude function is called and the output files are written every concfreq frames
rmin (float) – Minimal radial coordinate relative to the center of mass of the refgroup for evaluation (in Å).
rmax (float) –
Maximal radial coordinate relative to the center of mass of the refgroup for evaluation (in Å).
If
rmax=None
, the box extension is taken.bin_width (float) – Width of the bins (in Å).
grouping ({
"atoms"
,"residues"
,"segments"
,"molecules"
,"fragments"
}) –Atom grouping for the calculations.
The possible grouping options are the atom positions (in the case where
grouping="atoms"
) or the center of mass of the specified grouping unit (in the case wheregrouping="residues"
,"segments"
,"molecules"
or"fragments"
).bin_method ({
"com"
,"cog"
,"coc"
}) –Method for the position binning.
The possible options are center of mass (
"com"
), center of geometry ("cog"
), and center of charge ("coc"
).output (str) – Output filename.
dens ({
"mass"
,"number"
,"charge"
}) – density type to be calculated.
- results.bin_pos#
Bin positions (in Å) ranging from
rmin
tormax
.- Type:
- results.profile#
Calculated profile.
- Type:
- results.dprofile#
Estimated profile’s uncertainity.
- Type: