Search results for "derivati"
showing 10 items of 1360 documents
Benchmark coupled-cluster g-tensor calculations with full inclusion of the two-particle spin-orbit contributions.
2017
We present a parallel implementation to compute electron spin resonance g-tensors at the coupled-cluster singles and doubles (CCSD) level which employs the ACES III domain-specific software tools for scalable parallel programming, i.e., the super instruction architecture language and processor (SIAL and SIP), respectively. A unique feature of the present implementation is the exact (not approximated) inclusion of the five one- and two-particle contributions to the g-tensor [i.e., the mass correction, one- and two-particle paramagnetic spin-orbit, and one- and two-particle diamagnetic spin-orbit terms]. Like in a previous implementation with effective one-electron operators [J. Gauss et al.,…
An exact thermodynamical model of power-law temperature time scaling
2016
In this paper a physical model for the anomalous temperature time evolution (decay) observed in complex thermodynamical system in presence of uniform heat source is provided. Measures involving temperatures T with power-law variation in time as T(t)∝tβ with β∈R shows a different evolution of the temperature time rate T(t) with respect to the temperature time-dependence T(t). Indeed the temperature evolution is a power-law increasing function whereas the temperature time rate is a power-law decreasing function of time. Such a behavior may be captured by a physical model that allows for a fast thermal energy diffusion close to the insulated location but must offer more resistance to the therm…
Analytical Solutions for the Self- and Mutual Inductances of Concentric Coplanar Disk Coils
2013
In this paper, closed-form solutions are presented for the self- and mutual inductances of disk coils which lie concentrically in a plane. The solutions are given as generalized hypergeometric functions which are closely related to elliptic integrals. The method used is a Legendre polynomial expansion of the inductance integral, which renders all integrations straightforward. Excellent numerical agreement with previous studies is obtained. An asymptotic formula for the approach to the ring coil limit is also derived and numerically validated. The methods presented here can be applied to noncoaxial and noncoplanar cases.
Parallel Calculation of CCSD and CCSD(T) Analytic First and Second Derivatives.
2007
In this paper we present a parallel adaptation of a highly efficient coupled-cluster algorithm for calculating coupled-cluster singles and doubles (CCSD) and coupled-cluster singles and doubles augmented by a perturbative treatment of triple excitations (CCSD(T)) energies, gradients, and, for the first time, analytic second derivatives. A minimal-effort strategy is outlined that leads to an amplitude-replicated, communication-minimized implementation by parallelizing the time-determining steps for CCSD and CCSD(T). The resulting algorithm is aimed at affordable cluster architectures consisting of compute nodes with sufficient memory and local disk space and that are connected by standard co…
Frequency-modulated atomic force microscopy operation by imaging at the frequency shift minimum: the dip-df mode.
2014
In frequency modulated non-contact atomic force microscopy, the change of the cantilever frequency (Delta f) is used as the input signal for the topography feedback loop. Around the Delta f(z) minimum, however, stable feedback operation is challenging using a standard proportional-integral-derivative (PID) feedback design due to the change of sign in the slope. When operated under liquid conditions, it is furthermore difficult to address the attractive interaction regime due to its often moderate peakedness. Additionally, the Delta f signal level changes severely with time in this environment due to drift of the cantilever frequency f(0) and, thus, requires constant adjustment. Here, we pre…
Systematic study of octet-baryon electromagnetic form factors in covariant chiral perturbation theory
2017
We perform a complete and systematic calculation of the octet-baryon form factors within the fully covariant approach of SU(3) chiral perturbation theory at O(p^3). We use the extended on-mass shell renormalization scheme, and include explicitly the vector mesons and the spin-3/2 decuplet intermediate states. Comparing these predictions with data including magnetic moments, charges, and magnetic radii, we determine the unknown low-energy constants, and give predictions for yet unmeasured observables, such as the magnetic moment of the Sigma^0, and the charge and magnetic radii of the hyperons.
Thermally induced magnon accumulation in two-sublattice magnets
2016
We present a temperature-dependent study of the thermal excitation of a magnon accumulation in two-sublattice magnetic materials. Using atomistic spin model simulations, we study the local magnetization profiles sublattice-wise in the vicinity of a temperature step in antiferromagnets, as well as in ferrimagnets. It is shown that the strength of the magnon accumulation in these systems scales with the derivative of the magnetization with respect to the temperature. These results give an insight into the complex temperature dependence of the magnon accumulation by making a direct link to the macroscopic behavior of the magnetization.
Perturbative treatment of scalar-relativistic effects in coupled-cluster calculations of equilibrium geometries and harmonic vibrational frequencies …
2007
An analytic scheme for the computation of scalar-relativistic corrections to nuclear forces is presented. Relativistic corrections are included via a perturbative treatment involving the mass-velocity and the one-electron and two-electron Darwin terms. Such a scheme requires mixed second derivatives of the nonrelativistic energy with respect to the relativistic perturbation and the nuclear coordinates and can be implemented using available second-derivative techniques. Our implementation for Hartree-Fock self-consistent field, second-order Moller-Plesset perturbation theory, as well as the coupled-cluster level is used to investigate the relativistic effects on the geometrical parameters an…
Travelling Panels Made of Viscoelastic Material
2013
In this chapter, our focus is to analyse the behaviour of moving panels using viscoelastic materials. As the reader will have noticed, all the models discussed in previous chapters have concerned the case of a purely elastic material. The deformation of an elastic material depends only on the applied forces; it has no explicit time dependence. Paper, however, is a more complicated material: it is viscoelastic. In addition to elastic properties, it has also time-dependent viscous properties, which cause the phenomena of creep and relaxation (see, e.g., Alava and Niskanen 2006). One of the simplest models for a viscoelastic solid is the Kelvin–Voigt model, which consists of a linear spring an…
Relativistic corrections to electrical first-order properties using direct perturbation theory.
2008
Direct perturbation theory (DPT) is applied to compute relativistic corrections to electrical properties such as dipole moment, quadrupole moment, and electric-field gradient. The corrections are obtained as second derivatives of the energy and are given via method-independent expressions that involve the first derivative of the density matrix with respect to the relativistic perturbation as well as property integrals with additional momentum operators. Computational results obtained using Hartree-Fock (HF), second-order Moller-Plesset (MP2) perturbation theory, and the coupled-cluster singles and doubles approach augmented by a perturbative treatment of triple excitations are presented for…