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The mean-field approximation predicts pairing and shape phase transitions in nuclei as a function of temperature or excitation energy. However, in the finite nucleus the singularities of these phase transitions are smoothed out by quantal…

Nuclear Theory · Physics 2015-06-11 Y. Alhassid , C. Özen , H. Nakada

Using a combination of high-level ab initio electronic structure methods with efficient on-the-fly semiclassical evaluation of nuclear dynamics, we performed a massive scan of small polyatomic molecules searching for a long lasting…

Chemical Physics · Physics 2024-09-26 Alan Scheidegger , Jiří Vaníček , Nikolay V. Golubev

We experimentally obtained a direct image of the nuclear wave functions of {H_2}^+ by dissociating the molecule via electron attachment and determining the vibrational state using the COLTRIMS technique. Our experiment visualizes the nodal…

Atomic Physics · Physics 2012-02-20 L. Ph. H. Schmidt , T. Jahnke , A. Czasch , M. Schöffler , H. Schmidt-Böcking , R. Dörner

In this article we present a novel semi-analytical approach to calculate first-order electron-vibration coupling constants within the framework of density functional theory. It combines analytical expressions for the first-order derivative…

Mesoscale and Nanoscale Physics · Physics 2013-11-12 Marius Bürkle , Janne K. Viljas , Thomas J. Hellmuth , Elke Scheer , Florian Weigend , Gerd Schön , Fabian Pauly

Vibrational properties of molecules are of widespread interest and importance in chemistry and biochemistry. The reliability of widely employed approximate computational methods is questioned here against the complex experimental spectrum…

Chemical Physics · Physics 2025-09-24 Apurba Nandi , Riccardo Conte , Priyanka Pandey , Paul L. Houston , Chen Qu , Qi Yu , Joel M. Bowman

We investigate the characteristic effects of nuclear motion on attosecond transient absorption spectra in molecules by calculating the spectrum for different model systems. Two models of the hydrogen molecular ion are considered: one where…

Atomic Physics · Physics 2015-04-16 Jens E. Bækhøj , Lun Yue , Lars Bojer Madsen

In this paper we propose an ab initio method to solve quantum many-body problems of molecular dynamics where both the electronic and the nuclear degrees are represented by ensembles of trajectories and guiding waves in physical space. Both…

Atomic Physics · Physics 2025-01-28 Ivan P. Christov

The propagation of uncertainties in reaction cross sections and rates of neutron-, proton-, and $\alpha$-induced reactions into the final isotopic abundances obtained in nucleosynthesis models is an important issue in studies of…

High Energy Astrophysical Phenomena · Physics 2020-12-24 T. Rauscher

Conventional diagonalization methods to calculate nuclear energy levels in the framework of the configuration-interaction (CI) shell model approach are prohibited in very large model spaces. The shell model Monte Carlo (SMMC) is a powerful…

Nuclear Theory · Physics 2025-01-08 Y. Alhassid , M. Bonett-Matiz , C. N. Gilbreth , S. Vartak

We propose an accurate and efficient method to compute vibrational spectra of molecules, based on exact diagonalization of an algebraically calculated matrix based on powers of Morse coordinate. The present work focuses on the 1D potential…

Chemical Physics · Physics 2009-11-13 Andrea Bordoni , Nicola Manini

Quantum Monte Carlo methods are accurate and promising many body techniques for electronic structure calculations which, in the last years, are encountering a growing interest thanks to their favorable scaling with the system size and their…

Chemical Physics · Physics 2014-02-17 Andrea Zen , Ye Luo , Sandro Sorella , Leonardo Guidoni

In this article, we present a method for computing accurate and scalable nuclear forces within the phaseless auxiliary-field quantum Monte Carlo (AFQMC) framework. Our approach leverages automatic differentiation of the energy functional to…

Chemical Physics · Physics 2026-02-16 Jo S. Kurian , Ankit Mahajan , Sandeep Sharma

We extensively describe our recently established "divide-and-conquer" semiclassical method [M. Ceotto, G. Di Liberto and R. Conte, Phys. Rev. Lett. 119, 010401 (2017)] and propose a new implementation of it to increase the accuracy of…

Chemical Physics · Physics 2018-01-15 Giovanni Di Liberto , Riccardo Conte , Michele Ceotto

We present a Monte Carlo method for direct incorporation of nuclear inputs in primordial nucleosynthesis calculations. This method is intended to remedy shortcomings of current error estimation, by eliminating intermediate data evaluations…

Astrophysics · Physics 2009-10-31 Kenneth M. Nollett , Scott Burles

Actinides are of great interest in astrophysics and technology applications since they can fission. However, the microscopic calculation of their statistical properties in the presence of correlations poses a major theoretical challenge.…

Nuclear Theory · Physics 2026-02-13 D. DeMartini , Y. Alhassid

We determine the structure and energetics of complexes of the linear OCS molecule with small numbers of para-hydrogen molecules, N=1-8, using zero temperature quantum Monte Carlo methods. Ground state calculations are carried out with…

Atomic and Molecular Clusters · Physics 2009-11-10 F. Paesani , R. E. Zillich , K. B. Whaley

The detection of electron motion and electronic wavepacket dynamics is one of the core goals of attosecond science. Recently, choosing the nitric oxide (NO) molecule as an example, we have introduced and demonstrated a new experimental…

Atomic and Molecular Clusters · Physics 2015-04-17 Song Bin Zhang , Denitsa Baykusheva , Peter M. Kraus , Hans Jakob Wörner , Nina Rohringer

We study the effects of atomic vibrations on the solid-state chemical shielding tensor using first principles density functional theory calculations. At the harmonic level, we use a Monte Carlo method and a perturbative expansion. The Monte…

Materials Science · Physics 2014-10-07 Bartomeu Monserrat , Richard J. Needs , Chris J. Pickard

The very early stage of the coalescence of two nuclei is studied and used to estimate the nuclear viscosity. The time evolution of the neck region has been simulated by the unified Langevin equation method, which is used in the analysis of…

Nuclear Theory · Physics 2023-10-04 S. Amano , Y. Aritomo , M. Ohta

The shell model Monte Carlo (SMMC) approach provides a powerful method for the microscopic calculation of statistical and collective nuclear properties in model spaces that are many orders of magnitude larger than those that can be treated…

Nuclear Theory · Physics 2015-06-11 Y. Alhassid , A. Mukherjee , H. Nakada , C. Özen