Superconductivity of $La{H}_{10}$ and $La{H}_{16}$ polyhydrides

We explore high-pressure phase stability and superconductivity of lanthanum hydrides $La{H}_m$ (m=4-11,16). We predict stability of a hitherto unreported polyhydride $P6\mathrm{/}mmm$-$La{H}_{16}$ at pressures above 150 GPa; at 200 GPa its predicted superconducting $T_C$ is 156 K, critical field ${\mu }_0$$H_C$(0) ~ 35 T and superconducting gap is up to 35 meV. We revisit superconductivity of the recently discovered $La{H}_{10}$ and find its $T_C$ to be up to 259 K (170 GPa) from solving the Eliashberg equation and 271 K from solving the gap equation in SCDFT which also allowed us to compute the Coulomb pseudopotential ${\mu }^{\ast }$ for $La{H}_{10}$ and $La{H}_{16}$. Presence of several polymorph modifications of LaH10 may explain the variety in the experimentally measured $T_C$ values for $La{H}_{10}$ [1,2]