Abstract The variational quantum eigensolver (VQE) is a method that uses hybrid quantum-classical computational approach to find eigenvalues of Hamiltonian. VQE has been proposed as an alternative fully algorithms such phase estimation (QPE) because require hardware will not be accessible in the near future. successfully applied solve electronic Schrödinger equation for variety small molecules. However, scalability this limited by two factors: complexity circuits and classical optimization...

Dynamics at intersystem crossings are fundamental to many processes in chemistry, physics, and biology. The ab initio multiple spawning (AIMS) method was originally developed describe internal conversion dynamics conical intersections where derivative coupling is responsible for nonadiabatic transitions between electronic states with the same spin multiplicity. Here, applicability of AIMS extended crossing which different multiplicities mediated by relativistic spin–orbit coupling. In direct...

Simulating molecules using the Variational Quantum Eigensolver method is one of promising applications for NISQ-era quantum computers. Designing an efficient ansatz to represent electronic wave function crucial in such simulations. Standard unitary coupled-cluster with singles and doubles (UCCSD) tends have a large number insignificant terms that do not lower energy system. In this work, we present selective method, way construct iteratively selection procedure excitations up fourth order....

In this article, we review nonadiabatic molecular dynamics (NAMD) methods for modeling spin-crossover transitions. First, discuss different representations of electronic states employed in the grid-based and direct NAMD simulations. The nature interstate couplings is highlighted, with main focus on spin-orbit couplings. Second, describe three that have been used to simulate dynamics, including trajectory surface hopping, ab initio multiple spawning, multiconfiguration time-dependent Hartree....

We calculate the potential energy curves, permanent dipole moment and lifetimes of ground excited vibrational states heteronuclear alkali dimers XY (X, Y = Li, Na, K, Rb, Cs) in X(1)Σ(+) electronic state using coupled cluster with singles doubles triples method. All-electron quadruple-ζ basis sets additional core functions are used for Li small-core relativistic effective potentials quality Cs. The inclusion non-perturbative triple excitations is shown to be crucial obtaining accurate...

Abstract Influence of ordered monovacancies on elastic properties graphene is theoretically investigated by density functional theory (DFT) calculations. Inverse linear dependence the Young's modulus concentration vacancies has been revealed and migration rate calculated as a function applied strain. It shown that can be controlled applying various strains or temperatures. The influence magnetic well graphene‐like hexagonal carbon silicide (2D‐SiC) boron nitride (h‐BN) structures...

Accurate prediction of the intersystem crossing rates is important for many different applications in chemistry, physics, and biology. Recently, we implemented ab initio multiple spawning (AIMS) molecular dynamics method to describe processes, where nonradiative transitions between electronic states with spin multiplicities are mediated by spin-orbit coupling. Our original implementation direct AIMS used complete active space self-consistent field (CASSCF) coupled on which multidimensional...

The ab initio multiple spawning (AIMS) method enables nonadiabatic quantum molecular dynamics simulations in an arbitrary number of dimensions, with potential energy surfaces provided by electronic structure calculations performed on-the-fly. However, the intricacy AIMS algorithm complicates software development, deployment on modern shared computer resources, and postsimulation data analysis. PySpawn is a package that addresses these issues. program designed to be easily interfaced...

We investigate the lifetimes of vibrational states diatomic alkali-alkaline-earth cations to determine their suitability for ultracold experiments where long decoherence time and controllability by an external electric field are desirable. The potential energy permanent dipole moment curves ground electronic LiBe+, LiMg+, NaBe+, NaMg+ obtained using coupled cluster with singles doubles triples multireference configuration interaction methods in combination large all-electron cc-pCVQZ...

Most nonadiabatic molecular dynamics methods require the determination of a basis adiabatic or diabatic electronic states at every time step, but in dense manifolds states, such approaches become intractable. A notable exception is Ehrenfest dynamics, which can be implemented without explicit suffers from unphysical behavior when propagation on mean-field potential energy surface (PES) does not accurately reflect true multiple states. Here we introduce cloning for (MCDMS) method,...

A methodology to evaluate the kinetic stability of carbon nanostructures is presented based on assumption independent and random nature thermal vibrations. The directly correlated cleavage probability for weakest bond a given nanostructure. application method fullerenes nanotubes yields clear correlation their experimentally observed relative isomer abundances. general simple formulation ensures its applicability other which formation controlled by factors.

Iron oxide magnetite (Fe3O4) should be a reasonable analog for conception and understanding of the magnetic properties iron sulfide greigite (Fe3S4)—one most required materials having numerous applications but being far from complete now. We present here comparative study Mössbauer effect (ME) circular dichroism (MCD) spectroscopy Fe3O4 Fe3S4 nanoparticles. The ME spectrum parameters are shown to distinguish strongly that Fe3O4, MCD shapes absolutely different two compounds. To clarify...

The variational quantum eigensolver (VQE) is a method that uses hybrid quantum-classical computational approach to find eigenvalues and of Hamiltonian. VQE has been proposed as an alternative fully algorithms such phase estimation because require hardware will not be accessible in the near future. successfully applied solve electronic Schr\"{o}dinger equation for variety small molecules. However, scalability this limited by two factors: complexity circuits classical optimization problem....

Abstract We report the results of studying heat transfer in water heated by a cw laser with wavelengths 1.55 and 1.94 μm through optical fibres end-face radial outputs. It is shown that, depending on power wavelength radiation, implemented via convection, bubble boiling, or explosive boiling occurs asymmetrically, mainly forward − upward direction for fibre output output.

As quantum hardware continues to improve, more and application scientists have entered the field of computing. However, even with rapid improvements in last few years, devices, especially for chemistry applications, still struggle perform calculations that classical computers could not calculate. In lieu being able specific calculations, it is important a systematic way estimating resources necessary tackle problems. Standard arguments about computational complexity provide hope will be...

Solving the vibrational Schrödinger equation in neighborhood of conical intersections adiabatic representation is a challenge. At intersection point, first- and second-derivative nonadiabatic coupling matrix elements become singular, with singularity (diagonal Born-Oppenheimer correction) being non-integrable. These singularities result from discontinuities vibronic functions associated individual states, our group has recently argued that these divergent cancel when discontinuous sum to...

Ab initio molecular dynamics (AIMD) is a valuable technique for studying molecules and materials at finite temperatures where the nuclei evolve on potential energy surfaces obtained from accurate electronic structure calculations. In this work, we present an approach to running AIMD simulations noisy intermediate-scale quantum (NISQ)-era computers. The energies are calculated computer using variational eigensolver (VQE) method. Algorithms computation of analytical gradients entirely require...

As quantum hardware continues to improve, more and application scientists have entered the field of computing. However, even with rapid improvements in last few years, devices, especially for chemistry applications, still struggle perform calculations that classical computers could not calculate. In lieu being able specific calculations, it is important a systematic way estimating resources necessary tackle problems. Standard arguments about computational complexity provide hope will be...