Gauge-invariant real-space method for density functional calculations in an external magnetic field

2008 ◽  
Vol 77 (24) ◽  
Author(s):  
S. Janecek ◽  
E. Krotscheck
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Real Space ◽  
Gauge Invariant ◽  
Space Method

AN EFFICIENT DENSITY FUNCTIONAL ALGORITHM IN A STRONG MAGNETIC FIELD

2008 ◽  
Vol 22 (25n26) ◽  
pp. 4303-4314
Author(s):  
S. JANECEK ◽  
E. KROTSCHECK
Keyword(s):  
Magnetic Field ◽  
Density Functional ◽  
Real Space ◽  
Gauge Invariant ◽  
Invariant Formulation ◽  
Non Local ◽  
Structure Calculations ◽  
Invariant Configuration ◽  
Careful Assessment ◽  
Space Method

We describe the implementation of a manifestly gauge invariant configuration space method for ab initio electronic structure calculations in an arbitrarily strong external magnetic field. To be able to reproduce empirical data for realistic systems, we will also formulate our real-space algorithm in magnetic fields for non-local ionic pseudo-potentials. Numerical applications focus on two issues, namely a careful assessment of the convergence properties of our algorithm and in particular the implications of our gauge invariant formulation, and the calculation of NMR shifts for a number of typical molecules.

An improved scheme for the calculation of NMR chemical shifts in periodic systems based on gauge including atomic orbitals and density functional theory

2011 ◽  
Vol 89 (9) ◽  
pp. 1150-1161 ◽  
Author(s):  
Dmitry Skachkov ◽  
Mykhaylo Krykunov ◽  
Tom Ziegler
Keyword(s):  
Magnetic Field ◽  
Density Functional Theory ◽  
External Magnetic Field ◽  
Density Functional ◽  
Three Dimensional ◽  
Nuclear Magnetic Moment ◽  
Zero Order ◽  
Periodic Systems ◽  
Functional Theory ◽  
Atomic Orbitals

We report here on an improved first principles method that can determine NMR shielding tensors for periodic systems. Our scheme evaluates the shielding tensor as the second derivative of the total electronic energy with respect to a nuclear magnetic moment and an external magnetic field. Both the induced current density J(α) due to the first perturbation from the nuclear magnetic moment as well as the interaction of J(α) with the second perturbation in the form of an external magnetic field are evaluated analytically. Our approach is based on Kohn–Sham density functional theory and gauge-including atomic orbitals. It employs a Bloch basis set made up of Slater-type or numeric atomic orbitals and represents the Kohn–Sham potential fully without the use of effective core potentials. The method is implemented into the periodic program BAND. The new scheme represents an improvement over a previously proposed method in that use can be made of the zero-order Kohn–Sham orbitals from a calculation based on a primitive cell instead of a supercell. Further, J(α) is evaluated analytically rather than by a finite difference approach. The improvements reduce the required computational time by up to two orders of magnitude for three-dimensional systems. Such a reduction is made possible by the fact that we are using atomic centered basis functions. The new implementation is further able to take into account scalar relativistic effects within the zero-order regular approximation. Results from calculations of NMR shielding constants based on the present approach are presented for systems with one-, two-, and three-dimensional periodicity. The reported values are compared to experiment and results from the previously proposed scheme.

Kohn–Sham approach for fast hybrid density functional calculations in real-space numerical grid methods

2018 ◽  
Vol 230 ◽  
pp. 21-26 ◽  
Author(s):  
Jaewook Kim ◽  
Sungwoo Kang ◽  
Jaechang Lim ◽  
Sang-Yeon Hwang ◽  
Woo Youn Kim
Keyword(s):  
Density Functional Calculations ◽  
Density Functional ◽  
Real Space ◽  
Numerical Grid ◽  
Hybrid Density Functional

Large-scale real-space density-functional calculations: Moiré-induced electron localization in graphene

2015 ◽  
Vol 117 (11) ◽  
pp. 112811 ◽  
Author(s):  
Atsushi Oshiyama ◽  
Jun-Ichi Iwata ◽  
Kazuyuki Uchida ◽  
Yu-Ichiro Matsushita
Keyword(s):  
Density Functional Calculations ◽  
Density Functional ◽  
Large Scale ◽  
Real Space ◽  
Electron Localization ◽  
Space Density

scholarly journals Remarks on inverse electrodynamics

2021 ◽  
Vol 81 (10) ◽  
Author(s):  
Patricio Gaete ◽  
José A. Helayël-Neto
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Interaction Energy ◽  
Coulomb Potential ◽  
Nonlinear Electrodynamics ◽  
Gauge Invariant ◽  
Dependent Variables ◽  
Path Dependent ◽  
Formula Type ◽  
Bending Of Light

AbstractWe study physical aspects for a new nonlinear electrodynamics (inverse electrodynamics). It is shown that this new electrodynamics displays the vacuum birefringence phenomenon in the presence of external magnetic field, hence we compute the bending of light. Afterwards we compute the lowest-order modification to the interaction energy within the framework of the gauge-invariant but path-dependent variables formalism. Our calculations show that the interaction energy contains a long-range ($${1 \big / {{r^5}}}$$ 1 / r 5 -type) correction to the Coulomb potential.

Gauge invariant and gauge dependent aspects of topological walking colloidal bipeds

Soft Matter ◽  
2021 ◽  
Author(s):  
Mahla Mirzaee-Kakhki ◽  
Adrian Ernst ◽  
Daniel de las Heras ◽  
Maciej Urbaniak ◽  
Feliks Stobiecki ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Gauge Invariant ◽  
Magnetic Pattern ◽  
Colloidal Spheres

Paramagnetic colloidal spheres assemble to colloidal bipeds of various length in an external magnetic field and walk on a magnetic pattern.

scholarly journals Observation of anti-damping spin-orbit torques generated by in-plane and out-of-plane spin polarizations in MnPd3

2021 ◽  
Author(s):  
Mahendra DC ◽  
Ding-Fu Shao ◽  
Vincent Hou ◽  
Patrick Quarterman ◽  
Ali Habiboglu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
External Magnetic Field ◽  
Spin Polarization ◽  
Density Functional ◽  
Ferromagnetic Layer ◽  
Magnetic Memory ◽  
Spin Orbit ◽  
Logic Devices ◽  
Out Of Plane

Abstract High spin-orbit torques (SOTs) generated by topological materials and heavy metals interfaced with a ferromagnetic layer show promise for next generation magnetic memory and logic devices. SOTs generated from the in-plane spin polarization along y-axis originated by the spin Hall and Edelstein effects can switch magnetization collinear with the spin polarization in the absence of external magnetic fields. However, an external magnetic field is required to switch the magnetization along x and z-axes via SOT generated by y-spin polarization. Here, we present that the above limitation can be circumvented by unconventional SOT in magnetron-sputtered thin film MnPd3. In addition to the conventional in-plane anti-damping-like torque due to the y-spin polarization, out-of-plane and in-plane anti-damping-like torques originating from z-spin and x-spin polarizations, respectively have been observed at room temperature. The spin torque efficiency (θ_y) corresponding to the y-spin polarization from MnPd3 thin films grown on thermally oxidized silicon substrate and post annealed at 400 ℃ is 0.34 - 0.44 while the spin conductivity (σ_zx^y) is ~ 5.70 – 7.30× 105 ℏ⁄2e Ω-1m-1. Remarkably, we have demonstrated complete external magnetic field-free switching of perpendicular Co layer via unconventional out-of-plane anti-damping-like torque from z-spin polarization. Based on the density functional theory calculations, we determine that the observed x- and z- spin polarizations with the in-plane charge current are due to the low symmetry of the (114) oriented MnPd3 thin films. Taken together, the new material reported here provides a path to realize a practical spin channel in ultrafast magnetic memory and logic devices.

scholarly journals CONFINING POTENTIAL FROM INTERACTING MAGNETIC AND TORSION FIELDS

2010 ◽  
Vol 25 (06) ◽  
pp. 471-478
Author(s):  
PATRICIO GAETE ◽  
JOSÉ A. HELAŸEL-NETO
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Field Strength ◽  
Constant Electric Field ◽  
Static Potential ◽  
Gauge Invariant ◽  
Expectation Value ◽  
Confining Potential ◽  
Dependent Variables ◽  
Path Dependent

Adopting the gauge-invariant but path-dependent variables formalism, we study the coupling of torsion fields with photons in the presence of an external background electromagnetic. We explicitly show that, in the case of a constant electric field strength expectation value, the static potential remains Coulombic, while in the case of a constant magnetic field strength expectation value a confining potential is obtained. This result displays a marked qualitative departure from the usual coupling of axionlike particles with photons in the presence of an external magnetic field.

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