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We present first principles calculations of the magnetic moments and magnetic anisotropy energies of small Fe, Co and Ni clusters on top of a Ag(100) surface as well as the exchange-coupling energy between two single adatoms of Fe or Co on…

Materials Science · Physics 2009-11-07 B. Lazarovits , L. Szunyogh , P. Weinberger

We argue that to explain recent resonant tunneling experiments on crystals of Mn$_{12}$ and Fe$_8$, particularly in the low-T limit, one must invoke dynamic nuclear spin and dipolar interactions. We show the low-$T$, short-time relaxation…

Condensed Matter · Physics 2009-10-30 Nikolai Prokof'ev , Philip Stamp

Using the Green's function formalism, an ab initio theory for band structures of crystals is derived starting from the Hartree-Fock approximation. It is based on the algebraic diagrammatic construction scheme for the self-energy which is…

Other Condensed Matter · Physics 2007-05-23 Christian Buth , Uwe Birkenheuer , Martin Albrecht , Peter Fulde

We report an improved implementation for evaluating the analytical gradients of the random phase approximation (RPA) electron-correlation energy based on atomic orbitals and the localized resolution of identity scheme. The more efficient…

Materials Science · Physics 2024-04-17 Muhammad N. Tahir , Honghui Shang , Jia Li , Xinguo Ren

We study the magnetic relaxation of a system of localized spins interacting through weak dipole interactions, at a temperature large with respect to the ordering temperature but low with respect to the crystal field level splitting. The…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 A. Cuccoli , A. Fort , A. Rettori , E. Adam , J. Villain

We study the relaxation of a spin I that is weakly coupled to a quantum mechanical environment. Starting from the microscopic description, we derive a system of coupled relaxation equations within the adiabatic approximation. These are…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 W. Apel , Yu. A. Bychkov

We calculate the magnetisation relaxation in the short-time regime for an ensemble of nanomagnets in the presence of a low-frequency external AC biasing field, at temperatures lower than the magnetic anisotropy energy of the individual…

Condensed Matter · Physics 2007-05-23 G. Rose , P. C. E. Stamp

A wide variety of nuclear magnetic resonance experiments rely on the prediction and analysis of relaxation processes. Recently, innovative approaches have been introduced where the sample travels through a broad range of magnetic fields in…

We present a new scheme to extract numerically ``optimal'' interatomic potentials from large amounts of data produced by first-principles calculations. The method is based on fitting the potential to ab initio atomic forces of many atomic…

Condensed Matter · Physics 2009-10-22 Furio Ercolessi , James B. Adams

A recently modified method to enable low-energy nuclear scattering results to be extracted from the discrete energy levels of the target-projectile clusters confined by harmonic potential traps is tested. We report encouraging results for…

Nuclear Theory · Physics 2020-09-30 Xilin Zhang , S. R. Stroberg , P. Navrátil , Chan Gwak , J. A. Melendez , R. J. Furnstahl , J. D. Holt

We investigate the ability of Aufbau suppressed coupled cluster theory to act as a post-linear-response correction to widely used linear response methods for electronically excited states. We find that the theory is highly resilient to…

Chemical Physics · Physics 2025-06-23 Trine Kay Quady , Harrison Tuckman , Eric Neuscamman

We present ab-initio calculations of the magnetic moments and magnetic anisotropy energies of small FeCo clusters of varying composition on top of a Cu(100) substrate. Three different cluster layouts have been considered, namely 2x2, 3x3…

Materials Science · Physics 2007-05-23 C. Etz , B. Lazarovits , J. Zabloudil , R. Hammerling , B. Ujfalussy , L. Szunyogh , G. M. Stocks , P. Weinberger

We present an efficient \textit{ab initio} method for calculating the electronic structure and total energy of strongly correlated electron systems. The method extends the traditional Gutzwiller approximation for one-particle operators to…

Strongly Correlated Electrons · Physics 2014-07-01 Y. X. Yao , J. Liu , C. Liu , W. C. Lu , C. Z. Wang , K. M. Ho

We develop a framework that allows to calculate integrated properties of the nuclear response from first principles. Using the ab initio in-medium similarity renormalization group (IMSRG), we calculate the expectation values of moment…

Nuclear Theory · Physics 2025-11-10 Andrea Porro , Achim Schwenk , Alexander Tichai

Numerical modelling of coherent spin relaxation in nanomagnets, formed by magnetic molecules of high spins, is accomplished. Such a coherent spin dynamics can be realized in the presence of a resonant electric circuit coupled to the magnet.…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 V. I. Yukalov , V. K. Henner , P. V. Kharebov

The detailed investigation of electronic and magnetic properties of polymeric coordination materials with accurate ab initio quantum mechanical methods is often computationally extremely demanding because of the large number of atoms in the…

An ab-initio calculation scheme for finite nuclei based on self-consistent Green's functions in the Gorkov formalism is developed. It aims at describing properties of doubly-magic and semi-magic nuclei employing state-of-the-art microscopic…

Nuclear Theory · Physics 2015-05-30 V. Soma , T. Duguet , C. Barbieri

The atomic cluster expansion (Drautz, Phys. Rev. B 99, 014104 (2019)) is extended in two ways, the modelling of vectorial and tensorial atomic properties and the inclusion of atomic degrees of freedom in addition to the positions of the…

Computational Physics · Physics 2020-07-15 Ralf Drautz

We calculate from first principles the electronic structure, relaxation and magnetic moments in small Fe particles, applying the numerical local orbitals method in combination with norm-conserving pseudopotentials. The accuracy of the…

Materials Science · Physics 2009-11-07 A. V. Postnikov , P. Entel , Jose M. Soler

We compute moments of the isoscalar monopole response of N = Z closed-shell nuclei based on chiral nucleon-nucleon plus three-nucleon interactions. We employ the random phase approximation (RPA) and two ab initio many-body approaches, the…

Nuclear Theory · Physics 2026-03-03 Francesca Bonaiti , Andrea Porro , Sonia Bacca , Achim Schwenk , Alexander Tichai