Advantages of the DFT Augmented Symmetry Approach to Simulations of the Chromium-Based Ring Cr8 within B3LYP Functional

B. Brzostowskia, M. Wojciechowskia, G. Kamieniarzb aInstitute of Physics, University of Zielona Góra, Prof. Szafrana 4a, 65-516 Zielona Góra, Poland bFaculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland

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The DFT estimates of magnetic couplings in molecular nanomagnets are computationally demanding and their values have not achieved the satisfactory accuracy in spite of a lot of effort. We concentrate here on comprehensive tests for predictions of the recently proposed augmented symmetry approach aiming at reducing the computational complexity of the DFT calculations which is particularly important for the Wien2k code. Using the B3LYP functional, we demonstrate the numerical stability of magnetic couplings, magnetic moments and the HOMO-LUMO gaps, changing the fraction of exact exchange α. We reach the significant gain in the computing time without a loss in the accuracy of the final results with respect to those obtained by the standard PBE approach. We conclude that the value α=0.25 leads to best estimation of magnetic couplings for hybrid functionals within Wien2k.

DOI: 10.12693/APhysPolA.133.591 PACS numbers: 75.50.Xx, 71.15.Mb, 73.22.-f, 75.30.Et, 31.15.E