Torsion angle¶

A torsion angle is defined by four atoms $i,j,k,l$ by

$\theta = \sphericalangle \left( P_{ijk},P_{jkl} \right)$

where $P_{ijk}$ and $P_{jkl}$ are planes determined by the atoms $i,j,k$ and $j,k,l$ , respectively. It takes values from -180 to 180 degrees.

The use of the torsion angle is invoked by the following block in the meta-config.json file. The "atoms" keyword is used for the definition of the involved atoms in consecutive order:

"collective variables": [
  {
    "type": "torsion",
    "name": "torsion angle theta",
    "atoms": [i, j, k, l]
  },
  ...
]