  Modern cosmological surveys are delivering datasets characterized by
unprecedented quality and statistical completeness; this trend is expected to
continue into the future as new ground- and space-based surveys come online. In
order to maximally extract cosmological information from these observations,
matching theoretical predictions are needed. At low redshifts, the surveys
probe the nonlinear regime of structure formation where cosmological
simulations are the primary means of obtaining the required information. The
computational cost of sufficiently resolved large-volume simulations makes it
prohibitive to run very large ensembles. Nevertheless, precision emulators
built on a tractable number of high-quality simulations can be used to build
very fast prediction schemes to enable a variety of cosmological inference
studies. We have recently introduced the Mira-Titan Universe simulation suite
designed to construct emulators for a range of cosmological probes. The suite
covers the standard six cosmological parameters $\{\omega_m,\omega_b, \sigma_8,
h, n_s, w_0\}$ and, in addition, includes massive neutrinos and a dynamical
dark energy equation of state, $\{\omega_{\nu}, w_a\}$. In this paper we
present the final emulator for the matter power spectrum based on 111
cosmological simulations, each covering a (2.1Gpc)$^3$ volume and evolving
3200$^3$ particles. An additional set of 1776 lower-resolution simulations and
TimeRG perturbation theory results for the power spectrum are used to cover
scales straddling the linear to mildly nonlinear regimes. The emulator provides
predictions at the two to three percent level of accuracy over a wide range of
cosmological parameters and is publicly released as part of this paper.
