CCD: fragment insertion with cyclic coordinate descent to close chain breaks
KIC: robotics-inspired kinematic closure combined with random sampling of non-pivot loop torsions from Ramachandran space
next generation KIC: refined version of KIC; using omega sampling, neighbor-dependent Ramachandran distributions and ramping of rama and fa_rep score terms to achieve higher loop reconstruction performance and increase sampling of sub-Angstrom conformations (recommended algorithm if no fragment data is available)
KIC with fragments: fragment-based loop modeling using kinematic closure; combining the sampling powers of KIC and coupled phi/psi/omega degrees of freedom from protein fragment data to achieve higher loop reconstruction performance and the best sampling yet of sub-Angstrom conformations (recommended algorithm if fragment data is available)