6CYANA: angles split - CYANA command

Parameters: selection=<string>             (default: <blank>)
            structures=<integer>           (default: 1)
            decrease=<real>                (default: 4.0)
            all

Command to identify torsion angles that have a strong bimodal
distribution in the selected conformers. The analysis is performed
for the torsion angles matched by the selection <string>. By default,
the selection made in the most recent 'angles select' command is used,
or all angles if no selection has been made so far. However, torsion
angles that rotate only hydrogen atom , e.g. methyl groups rotations,
are considered only when the option 'all' is present.

Torsion angles whose values in the selected conformers cluster
into two distinct groups are identified by calculating the unimodal
standard deviation from a single mean value and the bimodal standard
deviation from two different mean values. A torsion angle distribution
is considered as clearly bimodal, or "split", if the bimodal standard
deviation is at least <decrease> times smaller than the conventional
unimodal standard deviation, and if the there are at least <structures>
conformers clustered in the smaller of the two groups. Split torsion
angle distributions are reported in a table.

For example:

    Split angles:    mean1  mean2    dev   # 1   5   10   15   20
    CHI1  VAL   33  -174.1  -73.2    2.1   4 +        +  +    +

In the example, CHI1 of Val 33 exhibits two distint conformations with
a small bimodal standard deviation of 2.1 degrees. The 4 conformers
1, 10, 13 and 18 that are marked with '+' are clustered around the
secondary mean value of -73.2 degrees. The other 16 conformers are
close to the first mean value of -174.1 degrees.

The 'angles split' command is included in the detailed overview
produced by the 'overview' macro.

See also: overview
