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== Parameters ==<br />
<br />
; selection=''string'': (default: ''none'')<br />
; structures=''integer'': (default: 1)<br />
; decrease=''real'': (default: 4.0)<br />
; all <br />
<br />
== Description ==<br />
<br />
Command to identify torsion angles that have a strong bimodal<br />
distribution in the selected conformers. The analysis is performed<br />
for the torsion angles matched by the selection ''string''. By default,<br />
the selection made in the most recent '''angles select''' command is used,<br />
or all angles if no selection has been made so far. However, torsion<br />
angles that rotate only hydrogen atom , e.g. methyl groups rotations,<br />
are considered only when the option '''all''' is present.<br />
<br />
Torsion angles whose values in the selected conformers cluster<br />
into two distinct groups are identified by calculating the unimodal<br />
standard deviation from a single mean value and the bimodal standard<br />
deviation from two different mean values. A torsion angle distribution<br />
is considered as clearly bimodal, or "split", if the bimodal standard<br />
deviation is at least ''decrease'' times smaller than the conventional<br />
unimodal standard deviation, and if the there are at least ''structures''<br />
conformers clustered in the smaller of the two groups. Split torsion<br />
angle distributions are reported in a table.<br />
<br />
For example:<br />
<br />
Split angles: mean1 mean2 dev # 1 5 10 15 20<br />
CHI1 VAL 33 -174.1 -73.2 2.1 4 + + + +<br />
<br />
In the example, CHI1 of Val 33 exhibits two distint conformations with<br />
a small bimodal standard deviation of 2.1 degrees. The 4 conformers<br />
1, 10, 13 and 18 that are marked with '''+''' are clustered around the<br />
secondary mean value of -73.2 degrees. The other 16 conformers are<br />
close to the first mean value of -174.1 degrees.<br />
<br />
The '''angles split''' command is included in the detailed overview<br />
produced by the '''overview''' macro.<br />
<br />
== See also ==<br />
<br />
* [[overview]]</div>Admin