alpha() -- make an $\alpha$ -helix

alpha(residues)

This makes restraints enforcing an $\alpha$ -helix (mainchain conformation class ``A'') for the residue segment specified by residues (which can be created using the model.residue_range() function). The helix is restrained by $\Phi,\Psi$ binormal restraints, N-O hydrogen bonds, ${C}_\alpha$ - ${C}_\alpha$ distances for $i-j \in \{2-9\}$ , ${C}_\alpha$ -O distances for $i-j \in \{2-9\}$ , and O-O distances for $i-j \in \{2-6\}$ ^6.1. Note that this requires all heavy atoms to be present to work properly, so will not work with the ${C}_\alpha$ -only topology.

To actually add the restraints, pass the new object to restraints.add(). See Section 2.2.9 for an example.