c2x binary package in Ubuntu Jammy amd64

 This program should convert CASTEP's .check, .castep_bin, orbitals and .cell
 to various other formats, particularly so that they can be visualised with
 Jmol, XCrysDen, gnuplot and other programs. It can extract change and spin
 densities, wavefunctions, symmetry operations, and much else besides. It also
 interfaces with VASP, Siesta, and other electronic structure codes.
 .
 The code can also manipulate .cell and .pdb files, building supercells
 or performing shifts.

Source package