Self-consistent phonon calculations were performed with ALAMODE . 3⇥3⇥2 and 4⇥4⇥4 primitive cells were used for tetragonal and cubic zirconia, respectively. Force constants were determined using compressive sensing. First a short (2 ps) ab initio molecular dynamics simulation was performed with VASP at a temperature of 1000 K and a step size of 2 fs. 50 equidistant configurations were extracted, and a random displacement of 0.1 Å was added to each atom to avoid strong correlations between configurations, and DFT calculations were performed on each of these configuration. Force constants were fitted using least absolute shrinkage and selection operator (LASSO) regression , for which the regularisation parameter was determined using 10-fold crossvalidation.