  First principles calculation supports the occurence of a phonon anomaly along
[211] in Ni$_2$FeGa that was observed experimentally for the first time as
structural modulations along [211] direction. Fermi surface scans have been
performed in both austenite and martensite phase to observe the possible Fermi
nesting features in the system. The magnitude of observed Fermi surface nesting
vectors in (211) plane exactly match the phonon anomaly wavevectors along [211]
direction. Electron-phonon calculations in the austenite phase shows that there
is significant electron-phonon coupling in the system which may arise out of
the lattice coupling between lower acoustic phonon modes and higher optical
phonon modes and also because of strong Fermi surface nesting features observed
in the system.
