Search results for "harmonic"

The Two Loop Crossed Ladder Vertex Diagram with Two Massive Exchanges

2008

We compute the (three) master integrals for the crossed ladder diagram with two exchanged quanta of equal mass. The differential equations obeyed by the master integrals are used to generate power series expansions centered around all the singular (plus some regular) points, which are then matched numerically with high accuracy. The expansions allow a fast and precise numerical calculation of the three master integrals (better than 15 digits with less than 30 terms in the whole real axis). A conspicuous relation with the equal-mass sunrise in two dimensions is found. Comparison with a previous large momentum expansion is made finding complete agreement.

Correction to ?partial spreads in finite projective spaces and partial designs?

1976

Conformational substates and dynamic properties of carbonmonoxy hemoglobin.

2003

Heme pocket dynamics of human carbonmonoxy hemoglobin (HbCO) is studied by Fourier transform infrared spectroscopy. The CO stretching band at various temperatures in the interval 300-10 K is analyzed in terms of three taxonomic A substates; however, in HbCO the band attributed to the A(1) taxonomic substate accounts for approximately 90% of the total intensity in the pH range 8.8-4.5. Two different regimes as a function of temperature are observed: below 160 K, the peak frequency and the bandwidth of the A(1) band have constant values whereas, above this temperature, a linear temperature dependence is observed, suggesting the occurrence of transitions between statistical substates within th…

Density functional theory (DFT) prediction of structural and spectroscopic parameters of cytosine using harmonic and anharmonic approximations

2015

The applicability of popular and efficient B3LYP hybrid density functional and medium-size Pople-type basis set in combination with computationally expensive anharmonic model to obtain more accurate theoretical structure, vibrational frequencies and GIAO NMR parameters of cytosine was tested. We report on prediction of cytosine equilibrium (R e ) and rovibrationally averaged (R v ) structures and vibrational frequencies in the gas phase and DMSO solution using density functional theory combined with 6-311++G** basis set. The harmonic and anharmonic vibrational frequencies (using second-order vibrational perturbation theory, VPT2) were critically discussed. In comparison with initial harmoni…

Finite-dimensional pseudo-bosons: a non-Hermitian version of the truncated harmonic oscillator

2018

We propose a deformed version of the commutation rule introduced in 1967 by Buchdahl to describe a particular model of the truncated harmonic oscillator. The rule we consider is defined on a $N$-dimensional Hilbert space $\Hil_N$, and produces two biorhogonal bases of $\Hil_N$ which are eigenstates of the Hamiltonians $h=\frac{1}{2}(q^2+p^2)$, and of its adjoint $h^\dagger$. Here $q$ and $p$ are non-Hermitian operators obeying $[q,p]=i(\1-Nk)$, where $k$ is a suitable orthogonal projection operator. These eigenstates are connected by ladder operators constructed out of $q$, $p$, $q^\dagger$ and $p^\dagger$. Some examples are discussed.

A no-go result for the quantum damped harmonic oscillator

2019

Abstract In this letter we show that it is not possible to set up a canonical quantization for the damped harmonic oscillator using the Bateman Lagrangian. In particular, we prove that no square integrable vacuum exists for the natural ladder operators of the system, and that the only vacua can be found as distributions. This implies that the procedure proposed by some authors is only formally correct, and requires a much deeper analysis to be made rigorous.

Relativistic coupled-cluster calculations on XeF6: Delicate interplay between electron-correlation and basis-set effects

2015

A systematic relativistic coupled-cluster study is reported on the harmonic vibrational frequencies of the O(h), C(3v), and C(2v) conformers of XeF6, with scalar-relativistic effects efficiently treated using the spin-free exact two-component theory in its one-electron variant (SFX2C-1e). Atomic natural orbital type basis sets recontracted for the SFX2C-1e scheme have been shown to provide rapid basis-set convergence for the vibrational frequencies. SFX2C-1e as well as complementary pseudopotential based computations consistently predicts that both O(h) and C(3v) structures are local minima on the potential energy surface, while the C(2v) structure is a transition state. Qualitative disagre…

Escala de desarrollo armónico (EDA): Una propuesta para la evaluación clínica del desarrollo infantil desde la Teoría de Sistemas

2020

Los profesionales de las ciencias de la salud y de la educación necesitan herramientas adecuadas para llevar a cabo la prevención de los trastornos del desarrollo infantil. La Escala de Desarrollo Armónico –EDA–, se presenta como una propuesta que permite la coordinación interdisciplinaria y la colaboración de los educadores. La escala se ha construido para observar el ascenso del paisaje epigenético individual desde el paradigma de los sistemas dinámicos. Para lograrlo, se han estudiado parámetros que pueden explicar la evolución del sistema –índice de armonía y cociente de desarrollo estable–, un mecanismo del cambio –tirón cognitivo– y fuerzas moldeadoras –velocidad y cristalización–, si…

Some geometric consequences of the Weitzenböck formula on Riemannian almost-product manifolds; weak-harmonic distributions

1988

On demontre des consequences geometriques obtenues a partir de certaines relations lineaires entre invariants lineaires de variete de Riemann presque-produit. On definit et on etudie des distributions faible-harmoniques

Harnack's inequality for p-harmonic functions via stochastic games

2013

We give a proof of asymptotic Lipschitz continuity of p-harmonious functions, that are tug-of-war game analogies of ordinary p-harmonic functions. This result is used to obtain a new proof of Lipsc...