  We report various phase transitions in half-Heusler TbPtBi compound using
Density Functional Theory (DFT). Specifically, inclusion of spin-orbit coupling
(SOC) leads to band inversion resulting in transition from the metallic to the
topological semimetallic phase. However, in presence of SOC, there is a phase
transition from the topological semimetal to the trivial semimetal when the
material is subjected to compressive strain ($\lt -7\%$). Subsequently, under
further increase of compressive strain ($\ge -7\%$), we find an opening of a
direct band gap at the $\Gamma$ point, driving the system from the trivial
semimetallic to the semiconducting state with changes in the sequence of bands.
In the absence of SOC, only transition from the metallic to the semiconducting
phase is noticed. Under tensile strain, the TbPtBi compound maintains its phase
as in the unstrained condition but with an increase in the hole pocket at the
Fermi level, both in the absence and presence of SOC. These tunable phase
transitions (especially as a fraction of strain) make this compound very
promising for application in various quantum devices such as highly sensitive
strain gauges.
