Site-specific atomic substitution in a giant magnetocaloric <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">Fe</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi mathvariant="normal">P</mml:mi></mml:math> -type system

Giant magnetocaloric (GMC) materials constitute a requirement for near room temperature magnetic refrigeration. (Fe,Mn)$_2$(P,Si) is GMC compound with strong magnetoelastic coupling. The main hindrance towards application of this material comparably large hysteresis, which can be reduced by metal site substitution nonmagnetic element. However, the has two equally populated sites, tetrahedrally coordinated $3f$ and pyramidally $3g$ sites. properties such compounds are highly sensitive to specific occupancy atoms. Here we have attempted study separately effect equal amounts vanadium. Using formation energy calculations, preference vanadium its influence on phase described. A difference in isothermal entropy change (as high as 44\%) sites observed. role lattice parameter strength coupling highlighted.