  In body-centered cubic (bcc) metals such as molybdenum, screw dislocations
often exhibit non-Schmid behavior, moving in directions unpredicted by the
Schmid law. The mobility of these dislocations is notably influenced by the
presence of solute atoms within the alloy matrix. In this study, employing
first-principles calculations, we delve into the electronic origins of these
influences.Initially, we construct both single atomic column and triple atomic
column models to simulate the formation of screw dislocations with solute
atoms. Our investigation reveals that tantalum (Ta) and tungsten (W) increase
the formation energy of solute-dislocation complexes, in contrast to osmium
(Os), iridium (Ir), and platinum (Pt). Subsequently, employing a comprehensive
screw dislocation dipole model under shear deformation, we explore the combined
effects of solute atoms and deformation on dislocation core movement. Our
findings demonstrate that Ta and W, positioned as first nearest neighbors,
reduce the stress required to move dislocation cores away from corresponding
dislocation dipoles. Conversely, Os, Ir, and Pt exhibit an attractive effect on
dislocation cores, lowering the energy barrier for screw dislocation formation
and enticing dislocation cores towards these solute atoms.
