  The physical properties of plutonium and plutonium-based intermetallic
compounds are extremely sensitive to temperature, pressure, and chemical
alloying. A celebrated example is the high-temperature $\delta$ phase
plutonium, which can be stabilized at room temperature by doping it with a few
percent trivalent metal impurities, such as gallium or aluminum. The cubic
phase Pu$_{3}$Ga, one of the plutonium-gallium intermetallic compounds, plays a
key role in understanding the phase stability and phase transformation of the
plutonium-gallium system. Its electronic structure might be essential to figure
out the underlying mechanism that stabilizes the $\delta$ phase
plutonium-gallium alloy. In the present work, we studied the
temperature-dependent correlated electronic states of cubic phase Pu$_{3}$Ga by
means of a combination of the density functional theory and the embedded
dynamical mean-field theory. We identified orbital selective 5$f$
itinerant-localized (coherent-incoherent) crossovers which could occur upon
temperature. Actually, there exist two well-separated electronic coherent
temperatures. The higher one is for the $5f_{5/2}$ state
[$T_{\text{coh}}(5f_{5/2}) \approx 700$ K], while the lower one is for the
$5f_{7/2}$ state [$T_{\text{coh}}(5f_{7/2}) \approx 100$ K]. In addition, the
quasiparticle multiples which originate from the many-body transitions among
the $5f^{4}$, $5f^{5}$, and $5f^{6}$ electronic configurations, decay
gradually. The hybridizations between the localized 5$f$ bands and conduction
bands are subdued by high temperature. Consequently, the Fermi surface topology
is changed, which signals a temperature-driven electronic Lifshitz transition.
Finally, the calculated linear specific heat coefficient $\gamma$ is
approximately 112 mJ / (mol K$^2$) at $T = 80$ K.
