Set here default visual data that does not depend of the atomic element.
Style
The
Style menu is to select the default atom visual representation.
Currently supported styles are: 1) a sphere, for
Solid; 2) a cross, for
Wired. The sphere gives a hight visual quality, when coupled with lights
and perhaps a perspective projection. A sphere uses considerable screen space
though and is time consuming.
The cross uses much less screen space and computing time. Moreover, when atoms
are bonded, crosses are not represented at all, and atoms are identified just
by the ends of the bond lines, decreasing even further computation needs.
However, wired objects do not have a 3D representation, so diffuse and
specular lights are not reflected, becoming poorly visible when using
lights, unless the ambient component is important, about (0.5, 0.5, 0.5).
Size
The
Size menu is to select the default atom size.
The intrinsic size of an atom is given by:
Size x (Variancy x Radius + (1 - Variancy) x Min)
where
Radius is the atom radius and
Min is the minimum
radius.
In
Wired mode, all atom crosses have a constant size, given by
Size x
Min, as
Variancy is
0.0.
In
Solid mode,
Size selects the default size of the atom spheres.
Combining default atom
Size and
Variancy with default bond
Size,
it is possible to obtain a wide range of styles to represent atomic structures.
In
Solid mode, the default is to represent atoms as constant
spheres (
Variancy =
0.0 and
Size =
0.8),
slightly larger than the bonds (
Size =
0.5). An elegant
style is to represent atoms as constant spheres with the same
Size
as bonds (
0.5).
To represent compact cristalline structures, atom
Size
and
Variancy must be
1.0, to be consistent with
cell dimensions. This style can also be used to represent molecules,
in order to emphasize the atomic radius and electronic distribution.
Variancy
Choose here the default value for
Variancy.
In
Wired mode,
Variancy is always
0.0.
In
Solid mode, by default
Variancy is
0.0 so the atom
spheres have all the same size. When
Variancy is
1.0 the atom
spheres are scaled directly by the atom radius.
Min
Min fixes the minimum size for crosses and spheres, as defined by
the equation above for
Size. By default this is the H covalent radius.