Questaal is usually compiled from source for your machine, fill out this form for repository access and once you get your invitation e-mail and login to the bitbucket project page read this tutorial for how to compile it.
In any work where you disseminate information where you used Questaal to generate a portion of it, please cite the following reference:
Dimitar Pashov, Swagata Acharya, Walter R. L. Lambrecht, Jerome Jackson, Kirill D. Belashchenko, Athanasios Chantis, Francois Jamet, Mark van Schilfgaarde, Questaal: a package of electronic structure methods based on the linear muffin-tin orbital technique, Comp. Phys. Comm. 249, 107065 (2020).
If you used the tbe code, please also cite:
M. W. Finnis, A. T. Paxton, M. Methfessel and M. van Schilfgaarde, Crystal Structures of Zirconia from First Principles and Self-Consistent Tight Binding, Phys. Rev. Lett. 81, 5149 (1998)
If you used the lmpg code, please also cite:
S. V. Faleev, F. Leonard, D. A. Stewart, and M. van Schilfgaarde, Ab initio tight-binding LMTO method for nonequilibrium electron transport in nanosystems, Phys. Rev. B71, 195422 (2005).
If you use the PMT method, please also cite:
T. Kotani and M. van Schilfgaarde, A fusion of the LAPW and the LMTO methods: the augmented plane wave plus muffin-tin orbital (PMT) method, Phys. Rev. B81, 125117 (2010).
If you use the GW package, please also cite:
Takao Kotani, M. van Schilfgaarde, S. V. Faleev, Quasiparticle self-consistent GW method: a basis for the independent-particle approximation Phys. Rev. B76, 165106 (2007).
The original density-functional code with a generalized LMTO basis set was first published in this book chapter:
M. Methfessel, Mark van Schilfgaarde, and R. A. Casali, “A full-potential LMTO method based on smooth Hankel functions,” in Electronic Structure and Physical Properties of Solids: The Uses of the LMTO Method, Lecture Notes in Physics 535, 114-147. H. Dreysse, ed. (Springer-Verlag, Berlin) 2000.
For references to classical work describing the LMTO basis, see this web page.