Linear-scaling aspherical crystallographic refinement of proteins: a case study for crambin and rubredoxin

Linear-scaling fragment Hirshfeld atom refinement has been implemented in Olex2 within the NoSpherA2 interface, which also solved previous issues with hydrogen bonds. This allowed the refinement of two small proteins, crambin and rubredoxin (the latter including a metal site), with quantum mechanical aspherical atomic form factors.