Rovibrational dynamics of the strontium molecule in the A^1\Sigma_u^+, c^3\Pi_u, and a^3\Sigma_u^+ manifold from state-of-the-art ab initio calculations

State-of-the-art ab initio techniques have been applied to compute the potential energy curves for the electronic states in the A^1\Sigma_u^+, c^3\Pi_u, and a^3\Sigma_u^+ manifold of the strontium dimer, the spin-orbit and nonadiabatic coupling matrix elements between the states in the manifold, and the electric transition dipole moment from the ground X^1\Sigma_g^+ to the nonrelativistic and relativistic states in the A+c+a manifold. The potential energy curves and transition moments were obtained with the linear response (equation of motion) coupled cluster method limited to single, double, and linear triple excitations for the potentials and limited to single and double excitations for the transition moments. The spin-orbit and nonadiabatic coupling matrix elements were computed with the multireference configuration interaction method limited to single and double excitations. Our results for the nonrelativistic and relativistic (spin-orbit coupled) potentials deviate substantially from recent ab initio calculations. The potential energy curve for the spectroscopically active (1)0_u^+ state is in quantitative agreement with the empirical potential fitted to high-resolution Fourier transform spectra [A. Stein, H. Knoeckel, and E. Tiemann, Eur. Phys. J. D 64, 227 (2011)]. The computed ab initio points were fitted to physically sound analytical expressions, and used in converged coupled channel calculations of the rovibrational energy levels in the A+c+a manifold and line strengths for the A^1\Sigma_u^+ <-- X^1\Sigma_g^+ transitions. Positions and lifetimes of quasi-bound Feshbach resonances lying above the ^1S + ^3P_1 dissociation limit were also obtained. Our results reproduce (semi)quantitatively the experimental data observed thus far. Predictions for on-going and future experiments are also reported.Comment: Final version, accepted for publication in Journal of Chemical Physic

Multiplication tenseur–vecteur haute performance sur des machines à memoire partagée

Tensor–vector multiplication is one of the core components in tensor computations. We have recently investigated high performance, single core implementation of this bandwidth-bound operation. In this work, we investigate efficient, shared memory algorithms to carry out this operation. Upon carefully analyzing the design space, we implement a number of alternatives using OpenMP and compare them experimentally. Experimental results on up to 8 socket systems show near peak performance for the proposed algorithms.La multiplication tenseur–vecteur est l’un des composants essentiels des calculs de tenseurs. Nous avons récemment étudié cette opération, qui consomme la bande passante, sur une plateforme séquentielle. Dans ce travail, nous étudions des algorithmes efficaces pour effectuer cette opérationsur des machines à mémoire partagée. Après avoir soigneusement analysé les différentes alternatives, nous mettons en œuvre plusieurs d’entre elles en utilisant OpenMP, et nous les comparons expérimentalement. Les résultats expérimentaux sur un à huit systèmes de sockets montrent une performance quasi maximale pour les algorithmes proposé

Visitation policies at palliative care units and stationary hospices during COVID-19 pandemic: A literature review

Background: The COVID-19 pandemic has significantly affected the ability of relatives and friends to accompany patients. Medical facilities have taken measures to limit or prohibit direct contact in proportion to the epidemic risk while respecting the integral health care component of relatives' participation in the therapeutic process. New challenges have also arisen in specialized palliative care units, where the family plays a key role in providing support and comfort to patients with advanced illness, especially at the end of life. This review aims to explore visitation policies in palliative care settings during the COVID-19 pandemic. Patients and methods: PubMed, SCOPUS and WOS were reviewed using iteratively selected keywords (visiting policy AND palliative care AND COVID-19) to identify visiting policies in specialist palliative care settings. Results: The presence of relatives and their direct participation in inpatient palliative care have been significantly reduced or completely excluded. Several units have established specific visiting policies designed to prevent patients, staff and visiting relatives from acquiring the infection. The rules included obligatory personal protective equipment, limiting the duration of visits and number of permitted guests, as well as allowing only visitors that had been vaccinated against COVID-19. To mitigate the harm caused by the restrictions, new means of remote contact such as video calls through teleconferencing platforms have been introduced or expanded. Conclusions: Delving into solutions facilitating contact between relatives and patients, implemented in inpatient palliative care units during the COVID-19 pandemic may serve to identify and establish model solutions for managing similar scenarios in the future

Website information on visiting policies at specialist in-patient palliative care settings during COVID-19 pandemic across Central and Eastern Europe: a quantitative and qualitative study

Introduction: Since the COVID-19 pandemic, visiting policies in various healthcare centers across the world have been changed. Patients' relatives and friends visits have been stopped or significantly limited. New conditions and legal constraints for family visits had to be implemented also at in-patient palliative care settings despite the fact that accompanying dying person is crucial for the quality of the end of life. The aim of the study was to identify and review the visiting policies at in-patient specialist palliative care settings across Central and Eastern Europe. Patients and methods: The study was conducted one year after the COVID-19 pandemic outbreak from May to October 2021. Information about visiting polices, published at official websites of the in-patient specialised palliative care settings (stationary hospices and hospital-based palliative care units) from Central and Eastern European countries, were identified and categorised. The websites with the lack of any information about visiting policy during COVID-19 pandemic were excluded. Qualitative and quantitative analysis of the obtained data was conducted by using content analysis techniques and descriptive analysis. The content from websites was translated into Polish with the usage of Google Translate machine tool. Results: Data from 55 in-patient palliative care settings from 8 countries were collected and analysed (83.6% from Poland, and the other from Bulgaria, Czech Republic, Estonia, Lithuania, Romania, Slovakia and Ukraine). In 43.6% of the organisations visits were stopped and 56.4% settings published information about the special requirements on visiting arrangements. In 32.7% of all examined units upfront approval from physician or the head of department for visiting a patient was required, and 29.1% published the information about personal protective equipment. 32.7% of organizations recommend telephone contact with the patient, and 12.7% provided video calls. Conclusions: Web information regarding visiting patients at in-patient palliative care settings is limited. There is a need to establish detailed requirements for the visits with better access to the website for the visitors, in case of global disease outbreak

Interaction between LiH molecule and Li atom from state-of-the-art electronic structure calculations

State-of-the-art ab initio techniques have been applied to compute the potential energy surface for the lithium atom interacting with the lithium hydride molecule in the Born–Oppenheimer approximation. The interaction potential was obtained using a combination of the explicitly correlated unrestricted coupled-cluster method with single, double, and noniterative triple excitations [UCCSD(T)-F12] for the core–core and core–valence correlation and full configuration interaction for the valence–valence correlation. The potential energy surface has a global minimum 8743 cm−1 deep if the Li–H bond length is held fixed at the monomer equilibrium distance or 8825 cm−1 deep if it is allowed to vary. In order to evaluate the performance of the conventional CCSD(T) approach, calculations were carried out using correlation-consistent polarized valence X-tuple-zeta basis sets, with X ranging from 2 to 5, and a very large set of bond functions. Using simple two-point extrapolations based on the single-power laws X−2 and X−3 for the orbital basis sets, we were able to reproduce the CCSD(T)–F12 results for the characteristic points of the potential with an error of 0.49% at worst. The contribution beyond the CCSD(T)–F12 model, obtained from full configuration interaction calculations for the valence–valence correlation, was shown to be very small, and the error bars on the potential were estimated. At linear LiH–Li geometries, the ground-state potential shows an avoided crossing with an ion-pair potential. The energy difference between the ground-state and excited-state potentials at the avoided crossing is only 94 cm−1. Using both adiabatic and diabatic pictures, we analyze the interaction between the two potential energy surfaces and its possible impact on the collisional dynamics. When the Li–H bond is allowed to vary, a seam of conical intersections appears at C2v geometries. At the linear LiH–Li geometry, the conical intersection is at a Li–H distance which is only slightly larger than the monomer equilibrium distance, but for nonlinear geometries it quickly shifts to Li–H distances that are well outside the classical turning points of the ground-state potential of LiH. This suggests that the conical intersection will have little impact on the dynamics of Li–LiH collisions at ultralow temperatures. Finally, the reaction channels for the exchange and insertion reactions are also analyzed and found to be unimportant for the dynamics

Femtosecond two-photon photoassociation of hot magnesium atoms: A quantum dynamical study using thermal random phase wavefunctions

Two-photon photoassociation of hot magnesium atoms by femtosecond laser pulses, creating electronically excited magnesium dimer molecules, is studied from first principles, combining \textit{ab initio} quantum chemistry and molecular quantum dynamics. This theoretical framework allows for rationalizing the generation of molecular rovibrational coherence from thermally hot atoms [L. Rybak \textit{et al.}, Phys. Rev. Lett. {\bf 107}, 273001 (2011)]. Random phase thermal wave functions are employed to model the thermal ensemble of hot colliding atoms. Comparing two different choices of basis functions, random phase wavefunctions built from eigenstates are found to have the fastest convergence for the photoassociation yield. The interaction of the colliding atoms with a femtosecond laser pulse is modeled non-perturbatively to account for strong-field effects

Formation of ultracold SrYb molecules in an optical lattice by photoassociation spectroscopy: theoretical prospects

State-of-the-art {\em ab initio} techniques have been applied to compute the potential energy curves for the SrYb molecule in the Born-Oppenheimer approximation for the ground state and first fifteen excited singlet and triplet states within the coupled-cluster framework. The leading long-range coefficients describing the dispersion interactions at large interatomic distances are also reported. The electric transition dipole moments have been obtained as the first residue of the polarization propagator computed with the linear response coupled-cluster method restricted to single and double excitations. Spin-orbit coupling matrix elements have been evaluated using the multireference configuration interaction method restricted to single and double excitations with a large active space. The electronic structure data was employed to investigate the possibility of forming deeply bound ultracold SrYb molecules in an optical lattice in a photoassociation experiment using continuous-wave lasers. Photoassociation near the intercombination line transition of atomic strontium into the vibrational levels of the strongly spin-orbit mixed $b^3\Sigma^+$, $a^3\Pi$, $A^1\Pi$, and $C^1\Pi$ states with subsequent efficient stabilization into the $v^{\prime\prime}=1$ vibrational level of the electronic ground state is proposed. Ground state SrYb molecules can be accumulated by making use of collisional decay from $v^{\prime\prime}=1$ to $v^{\prime\prime}=0$. Alternatively, photoassociation and stabilization to $v^{\prime\prime}=0$ can proceed via stimulated Raman adiabatic passage provided that the trapping frequency of the optical lattice is large enough and phase coherence between the pulses can be maintained over at least tens of microseconds

Coupled cluster theory on modern heterogeneous supercomputers

This study examines the computational challenges in elucidating intricate chemical systems, particularly through ab-initio methodologies. This work highlights the Divide-Expand-Consolidate (DEC) approach for coupled cluster (CC) theory—a linear-scaling, massively parallel framework—as a viable solution. Detailed scrutiny of the DEC framework reveals its extensive applicability for large chemical systems, yet it also acknowledges inherent limitations. To mitigate these constraints, the cluster perturbation theory is presented as an effective remedy. Attention is then directed towards the CPS (D-3) model, explicitly derived from a CC singles parent and a doubles auxiliary excitation space, for computing excitation energies. The reviewed new algorithms for the CPS (D-3) method efficiently capitalize on multiple nodes and graphical processing units, expediting heavy tensor contractions. As a result, CPS (D-3) emerges as a scalable, rapid, and precise solution for computing molecular properties in large molecular systems, marking it an efficient contender to conventional CC models

Family - Health - Disease

Preface: "The family is the basic social cell and a person’s closest environment; it plays the dominant non-medical role in shaping health as it is the primary source of knowledge about nutrition, life-style and disease prevention. The family may determine both healthy habits and anti-health behaviors; it influences the entire duration of a person’s life. It is important to emphasize the extremely significant role of the family in providing care, supporting treatment processes, and giving company to an ill family member."(...