Dresden 2026 – scientific programme

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MA: Fachverband Magnetismus

MA 42: Molecular Magnetism and Magnetic Particles / Clusters II

MA 42.8: Talk

Thursday, March 12, 2026, 11:30–11:45, HSZ/0004

Symmetric finite-temperature Lanczos method for anisotropic magnetic molecules — •Jürgen Schnack — Bielefeld University, Faculty of Physics, Bielefeld, Germany

The finite-temperature Lanczos method (FTLM) constitutes a valuable approximation scheme for Hilbert space problems that exceed the dimension tractable by complete numerical diagonalization [1,2]. Several large magnetic molecules have been successfully modeled using FTLM [3]. It has been noted earlier that the method converges best for problems where the z-component of total spin commutes with the Hamiltonian. For anisotropic Hamiltonians the convergence is much poorer [4]. Here, we discuss conceptional improvements [5] as well as realizations on nowadays supercomputing architectures that employ CPUs as well as GPUs.

[1] J. Jaklic, P. Prelovsek, Phys. Rev. B 49, 5065 (1994). [2] J. Schnack, J. Richter, R. Steinigeweg, Phys. Rev. Research 2, 013186 (2020). [3] T. Tziotzi, D. Gracia, S. Dalgarno, J. Schnack, M. Evangelisti, E. Brechin, C.J. Milios, JACS 145, 7743 (2023). [4] O. Hanebaum, J. Schnack, Eur. Phys. J. B 87, 194 (2014). [5] M. Aichhorn, M. Daghofer, H. G. Evertz, W. von der Linden, Phys. Rev. B 67, 161103(R) (2003).

Keywords: finite-temperature Lanczos method; magnetic molecules; anisotropic Hamiltonian