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We present a fully parameter-free density-functional approach for the accurate description of optical absorption spectra of insulators, semiconductors and metals. We show that this can be achieved within time-dependent…

Materials Science · Physics 2015-10-28 J. A. Berger

We propose a way of obtaining effective low energy Hubbard-like model Hamiltonians from ab initio Quantum Monte Carlo calculations for molecular and extended systems. The Hamiltonian parameters are fit to best match the ab initio two-body…

Strongly Correlated Electrons · Physics 2015-08-06 Hitesh J. Changlani , Huihuo Zheng , Lucas K. Wagner

We developed a semiclassical approximation method in combination with an adaptive moment estimation optimizer (SCA + ADAM) approach based on the PyTorch plus CUDA library on a the graphics processing unit (GPU). This method was employed to…

Strongly Correlated Electrons · Physics 2023-11-09 Hayun Park , Hunpyo Lee

Two-parameter perturbation theory is a scheme tailor-made to consistently include nonlinear density contrasts on small scales ($<100\; \mathrm{Mpc}$), whilst retaining a traditional approach to cosmological perturbations in the…

General Relativity and Quantum Cosmology · Physics 2020-03-18 Christopher Gallagher , Timothy Clifton , Chris Clarkson

We develop and analyze a fault-tolerant quantum algorithm for computing $n$-th order response properties necessary for analysis of non-linear spectroscopies of molecular and condensed phase systems. We use a semi-classical description in…

Quantum Physics · Physics 2024-04-23 Tyler Kharazi , Torin F. Stetina , Liwen Ko , Guang Hao Low , K. Birgitta Whaley

In this paper we analyze a greedy procedure to approximate a linear functional defined in a Reproducing Kernel Hilbert Space by nodal values. This procedure computes a quadrature rule which can be applied to general functionals, including…

Numerical Analysis · Mathematics 2021-05-19 Gabriele Santin , Toni Karvonen , Bernard Haasdonk

A singularly perturbed linear system of second order partial differential equations of parabolic reaction-diffusion type with given initial and boundary conditions is considered. The leading term of each equation is multiplied by a small…

Numerical Analysis · Mathematics 2010-08-17 V. Franklin , M. Paramasivam , S. Valarmathi , J. J. H. Miller

We consider a multiband Hubbard model $H_m$ for Cu and O orbitals in Ba$_{2-x}$Sr$_x$CuO$_{3+\delta}$ similar to the tree-band model for two-dimensional (2D) cuprates. The hopping parameters are obtained from maximally localized Wannier…

Strongly Correlated Electrons · Physics 2024-05-29 Adrian E. Feiguin , Christian Helman , Armando A. Aligia

A novel approach to the description of superconductors in thermal equilibrium is developed within a formally exact density-functional framework. The theory is formulated in terms of three ``densities'': the ordinary electron density, the…

We explore non-canonical scalar field model in the background of non-flat $D$-dimensional fractal Universe with cosmological constant $\Lambda$ on the condition that the matter and scalar field are separately conserved. The potential $V$,…

General Relativity and Quantum Cosmology · Physics 2019-10-02 Ujjal Debnath , Kazuharu Bamba

The non-linear response of infinite periodic solids to homogenous electric fields and collective atomic displacements is discussed in the framework of density functional perturbation theory. The approach is based on the 2n + 1 theorem…

Materials Science · Physics 2007-05-23 M. Veithen , X. Gonze , Ph. Ghosez

We develop the no-propagate algorithm for sampling the linear response of random dynamical systems, which are non-uniform hyperbolic deterministic systems perturbed by noise with smooth density. We first derive a Monte-Carlo type formula…

Dynamical Systems · Mathematics 2023-08-16 Angxiu Ni

We present a new efficient method for computing the non-linearity parameters of the higher order correlation functions of local type curvature perturbations in inflation models having a $\cal N$-component scalar field, focusing on the…

Astrophysics · Physics 2014-11-18 Shuichiro Yokoyama , Teruaki Suyama , Takahiro Tanaka

The power of multivariate functions is their ability to model a wide variety of phenomena, but have the disadvantages that they lack an intuitive or interpretable representation, and often require a (very) large number of parameters. We…

Numerical Analysis · Computer Science 2018-05-23 Philippe Dreesen , Jeroen De Geeter , Mariya Ishteva

This paper deals with the problem of estimating second-order parameter sensitivities for stochastic reaction networks, where the reaction dynamics is modeled as a continuous time Markov chain over a discrete state space. Estimation of such…

Probability · Mathematics 2014-07-29 Ankit Gupta , Mustafa Khammash

Eclipsing binaries provide one of the most direct mechanisms for measuring stellar properties such as mass and radius, but historically, determining these properties has been non-trivial and computationally prohibitive. As such, only a…

We present a complexity reduction algorithm for a family of parameter-dependent linear systems when the system parameters belong to a compact semi-algebraic set. This algorithm potentially describes the underlying dynamical system with…

Systems and Control · Computer Science 2012-09-25 Farhad Farokhi , Henrik Sandberg , Karl H. Johansson

We present an extensive comparison of models of structure formation with observations, based on linear and quasi-linear theory. We assume a critical matter density, and study both cold dark matter models and cold plus hot dark matter…

Astrophysics · Physics 2015-06-24 Andrew R Liddle , David H Lyth , R K Schaefer , Q Shafi , Pedro T P Viana

Generally, natural scientific problems are so complicated that one has to establish some effective perturbation or nonperturbation theories with respect to some associated ideal models. In this Letter, a new theory that combines…

Computational Physics · Physics 2015-05-13 Yuan Gao , S. Y. Lou

The problem of identifiability of model parameters for open quantum systems is considered by investigating two-level dephasing systems. We discuss under which conditions full information about the Hamiltonian and dephasing parameters can be…

Quantum Physics · Physics 2015-01-15 Er-ling Gong , Weiwei Zhou , S. G. Schirmer , Zhi-Qiang Sun , Ming Zhang
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