  Simulating solids with quantum chemistry methods and Gaussian-type orbitals
(GTOs) has been gaining popularity. Nonetheless, there are few systematic
studies that assess the basis set incompleteness error (BSIE) in these
GTO-based simulations over a variety of solids. In this work, we report a
GTO-based implementation for solids, and apply it to address the basis set
convergence issue. We employ a simple strategy to generate large uncontracted
(unc) GTO basis sets, that we call the unc-def2-GTH sets. These basis sets
exhibit systematic improvement towards the basis set limit as well as good
transferability based on application to a total of 43 simple semiconductors.
Most notably, we found the BSIE of unc-def2-QZVP-GTH to be smaller than 0.7
m$E_h$ per atom in total energies and 20 meV in band gaps for all systems
considered here. Using unc-def2-QZVP-GTH, we report band gap benchmarks of a
combinatorially designed meta generalized gradient functional (mGGA), B97M-rV,
and show that B97M-rV performs similarly (a root-mean-square-deviation (RMSD)
of 1.18 eV) to other modern mGGA functionals, M06-L (1.26 eV), MN15-L (1.29
eV), and SCAN (1.20 eV). This represents a clear improvement over older pure
functionals such as LDA (1.71 eV) and PBE (1.49 eV) though all these mGGAs are
still far from being quantitatively accurate. We also provide several
cautionary notes on the use of our uncontracted bases and on future research on
GTO basis set development for solids.
