In order to extract the tensor principal components along with the Euler angles relating the shift and quadrupolar tensors we fitted the 2D static adiabatic shifting d-echo spectra using SIMPSON-simulated spectra with a Levenberg-Marquardt damped least-square minimization algorithm implemented in C++. The errors of the values were evaluated using an inhouse Monte Carlo procedure, which has been described in detail previously. Density functional theory (DFT) calculations were carried out using the Quantum ESPRESSO , WIEN2k and ORCA packages.