Chimera Commands Index
### Usage:

**aniso** [ **spec**
*atom-spec* ]
[ **color** *colorname* ] [ **scale** *factor* ]
[ **smoothing** *level* ]

**Aniso** is the command-line implementation of
**Thermal
Ellipsoids**, which
generates ellipsoids to show atomic anisotropic B-factors.
Anisotropic B-factors are read from the input coordinate file
(for example, from ANISOU records in a PDB file)
and are included with only certain high-resolution structures.
Thermal ellipsoids will be created only for atoms with such information.
Ellipsoid axes and radii correspond to the eigenvectors and eigenvalues
of the atomic mean-square displacement matrix.
The radii are proportional to the root-mean-square displacements (RMSDs),
the square roots of the eigenvalues.

Unless restricted to certain atoms with the **spec** option,
the command **aniso** removes any pre-existing ellipsoids and
generates new ones for just the currently displayed atoms.
The command **~aniso** removes ellipsoids.
Option keywords for **aniso** are case-independent
and can be truncated to unique strings:

**spec**
*atom-spec*

Create/remove ellipsoids for just the
specified atoms.
Ellipsoids will be created only for atoms that are also displayed.

**color** *colorname*

Color to use for the ellipsoids.
The *colorname* can be **none** (default, meaning to match
the corresponding atoms) or any
color name that specifies a single color.

**scale** *factor*

Adjust the size of the ellipsoids by a constant *factor*
(default **1.0**, no scaling). The unscaled ellipsoid radii
equal the atomic RMSDs along the ellipsoid axes.
The scaling factor for 50% probability is 1.5382.
The **Thermal
Ellipsoids** interface can be used to calculate the scaling factor
for any probability ≥ 0% and < 100%.

**smoothing** *level*

The *level* (default **1**)
controls how many planar facets are used to draw each ellipsoid.
Higher values give smaller facets and smoother ellipsoids.

See also:
**measure inertia**,
**Render by
Attribute**,
**Axes/Planes**