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To investigate hydrogen behaviors in the high-entropy alloy AlCrTiNiV, density functional theory and transition state theory were used to explore the molecular H 2 absorption and dissociation and the atomic H adsorption, diffusion, and penetration progress. The H 2 molecule, where the H-H band is parallel to the surface layer, is more inclined to absorb on the top site of the Ti atom site of first atomic layer on the AlCrTiNiV surface, then diffuse into the hollow sites, through the bridge site, after dissociating into two H atoms. Atomic H is more likely to be absorbed on the hollow site. The absorption capacity for atomic H on the surface tends to decline with the increase in H coverage. By calculating the energy barriers of atomic H penetration in AlCrTiNiV, it was indicated that lattice distortion may be one important factor that impacts the permeation rate of hydrogen. Our theory research suggests that high-entropy alloys have potential for use as a hydrogen resistant coating material. [ABSTRACT FROM AUTHOR]

Besifloxacin is a fourth-generation fluoroquinolone and shows significant antibacterial properties, which works well against a range of bacteria. Besifloxacin ophthalmic solution is the name of the specific form of this medication used to treat eye infections. The vortex-assisted chiral ionic liquid method was used for the separation of Besifloxacin isomers. S-Besifloxacin shows antibacterial action in clinical trials. The R-isomer, however, has not shown biological properties in clinical testing through different cell line. The current proposed chiral assay method was developed between a racemic mixture and a chiral selector. The analytical databases affirm that 1, 2 dichloroethane is used as a non-aqueous (organic media) solvent and that 1,3-butyl-3-methylimidazole L-tryptophan ([Bmim] [Ltrp]) opted used as a specific chiral ionic liquid. The developed ionic liquid based chital hplc method was successfully applied to separation and purification of isomers of Besifloxacin in during the process industries in bulk drugs. [ABSTRACT FROM AUTHOR]

Micellar aqueous solutions of ionic surfactants have been observed to exhibit proton delocalization (the nuclear quantum effect) and to oscillate between a low density (LDL) and a high-density liquid (HDL) state of water at a fixed temperature. It is shown in this paper that such phenomena can be explained with the help of the interpolating Schrӧdinger equation proposed by Ghose. The nuclear quantum effect can be described by the tunneling of a harmonic oscillator in a symmetric double-well potential, and an ensemble of harmonic oscillators can model the LDL-HDL oscillations. The thermodynamics of such harmonic oscillators has been worked out showing continuous transitions between the quantum and classical limits. [ABSTRACT FROM AUTHOR]

To investigate hydrogen behaviors in the high-entropy alloy AlCrTiNiV, density functional theory and transition state theory were used to explore the molecular H2 absorption and dissociation and the atomic H adsorption, diffusion, and penetration progress. The H2 molecule, where the H-H band is parallel to the surface layer, is more inclined to absorb on the top site of the Ti atom site of first atomic layer on the AlCrTiNiV surface, then diffuse into the hollow sites, through the bridge site, after dissociating into two H atoms. Atomic H is more likely to be absorbed on the hollow site. The absorption capacity for atomic H on the surface tends to decline with the increase in H coverage. By calculating the energy barriers of atomic H penetration in AlCrTiNiV, it was indicated that lattice distortion may be one important factor that impacts the permeation rate of hydrogen. Our theory research suggests that high-entropy alloys have potential for use as a hydrogen resistant coating material.

The zero-point energies (ZPEs) of paramagnetic molecules, free and compressed in a C59N paramagnetic cage, were computed. The excess of energy acquired by molecules under compression depended on the deuterium and tritium isotopes which ranged from 6–8 kcal/mol for H2+ to 1.0–1.5 kcal/mol for HO• and HO2. The differences in the ZPEs of compressed isotopic molecules resulted in large deuterium and tritium isotope effects which differed for singlet and triplet spin states. The hyperfine coupling (HFC) constants for protons and 17O nuclei decreased under compression, confirming the leakage of the unpaired π-electron from the central oxygen atom of guest molecules into the system of π-electrons of the cage, and its distribution over 60 atoms of the C59N. The latter seems to be the reason why the nitrogen-14 HFCs for C59N remain almost unchanged upon encapsulation of guest molecules. The singlet-triplet splitting is shown to depend on the Coulomb interaction, which controls the sign of the exchange potential. The importance of compression effects on the functioning of enzymes as molecular compressing devices is discussed.

This paper presents a theoretical calculation of the vacuum energy density by summing the contributions of all quantum fields' vacuum states, which turns out to indicate that there seems to be a missing bosonic contribution in order to match the predictions of the current cosmological models and all observational data to date. The basis for this calculation is a new Zeta function regularization method used to tame the infinities present in the improper integrals of power functions. The paper also presents a few other contributions in the area of vacuum energy. [ABSTRACT FROM AUTHOR]

• A semi-empirical parameter, M , is proposed to measure the material's ability to absorb energy. • The M is closely related to the zero-point energy and lattice volume of the material. • A larger value of M ∗ indicates that the energetic material has a lower impact sensitivity. Measuring the ability of a material to absorb energy from an external stimulus is crucial for understanding the sensitivity mechanism of energetic materials (EMs). Based on this, a semi-empirical parameter, M , is proposed to measure the material's ability to absorb energy from an external stimulus, which is closely related to zero-point energy and volume. In this work, taking the external pressures (P) of 0.1 and 1.0 GPa as examples, we calculate the value of M for 16 EMs, and discuss the relationship between M and the impact sensitivity of EMs (E 50). Considering the indispensable influence of molecular structure on the impact sensitivity of EMs, 16 EMs are divided into Groups A and B according to their structure whether contains a benzene ring. We find that the correlation between M 0 and E 50 when P is 0.1 GPa is less than that when P is 1.0 GPa. Therefore, the parameter M 0 has been modified by adding the initial zero-point energy, and the modified parameter is referred to as M ∗. The correlation between M ∗ and E 50 is further improved compared with M 0. In particular, for Group B, the correlation between M ∗ and E 50 is good, where R2 is 0.95 and PCCs is 0.97 when P is 1.0 GPa, and R2 is 0.87 and PCCs is 0.92 when P is 0.1 GPa. [ABSTRACT FROM AUTHOR]

Ambimodal reactions involve a single transition state leading to multiple products. To assess the ratio of the bifurcation products, quasiclassical trajectories (QCTs) are initiated from transition state geometries that are randomly sampled using the zero‐point energy (ZPE) plus thermal energy of a molecule's vibrational modes. However, in the QCTs, the influence of ZPE percentage in the resulting bifurcation ratio and time gap between formation of bonds is not well understood. To benchmark the effect of varying the percentage of the molecules' inherent ZPE used in the simulation, three organic reactions with distinct mechanisms that all display post‐transition state bifurcation were selected. The three reactions studied include an intramolecular [6 + 4]/[4 + 2] cycloaddition, an asynchronous nitrene insertion, and an SN2/addition to a carbonyl on an α‐bromoketone. These reactions encompass various modes of bond formation and cleavage, offering a broad view of the influence of ZPE scaling in evaluating the product ratio resulted from post‐transition state bifurcation. Exploring means of tuning selectivity in simulation enables development of more accurate organic reaction modeling for synthetic prediction. This work will establish a basis for future QCT studies of organic reactions. [ABSTRACT FROM AUTHOR]

The Stefan–Boltzmann (SB) law relates the radiant emittance of an ideal black-body cavity at thermal equilibrium to the fourth power of the absolute temperature T as q = σ T 4 , with σ = 5. 6 7 × 1 0 − 8 W m − 2 K − 4 the SB constant, first estimated by Stefan to within 1 1 % of the present theoretical value. The law is an important achievement of modern physics since, following Planck [Ueber das Gesetz der Energieverteilung im Normalspectrum [On the law of distribution of energy in the normal spectrum], Ann. Phys. 4 (1901) 553–563], its microscopic derivation implies the quantization of the energy related to the electromagnetic field spectrum. Somewhat astonishing, Boltzmann presented his derivation in 1878 making use only of electrodynamic and thermodynamic classical concepts, apparently without introducing any quantum hypothesis (here called first Boltzmann paradox). By contrast, the Boltzmann derivation implies two assumptions not justified within a classical approach, namely: (i) the zero value of the chemical potential and (ii) the internal energy of the black body with a finite value and dependent from both temperature and volume. By using Planck [Ueber das Gesetz der Energieverteilung im Normalspectrum [On the law of distribution of energy in the normal spectrum], Ann. Phys. 4 (1901) 553–563] quantization of the radiation field in terms of a gas of photons, the SB law received a microscopic interpretation free from the above assumptions that also provides the value of the SB constant on the basis of a set of universal constants including the quantum action constant h. However, the successive consideration by Planck [Uber die Begründung des Gesetzes der schwarzen Strahlung [On the grounds of the law of black body radiation], Ann. Phys. 6 (1912) 642–656] concerning the zero-point energy contribution was found to be responsible of another divergence of the internal energy for the single photon mode at high frequencies. This divergence is of pure quantum origin and is responsible for a vacuum-catastrophe, to keep the analogy with the well-known ultraviolet catastrophe of the classical black-body radiation spectrum, given by the Rayleigh–Jeans law in 1900. As a consequence, from a rigorous quantum-mechanical derivation we would expect the divergence of the SB law (here called second Boltzmann paradox). Here, both the Boltzmann paradoxes are revised by accounting for both the quantum-relativistic photon gas properties, and the Casimir force. [ABSTRACT FROM AUTHOR]

It was long believed that there is a zero-point energy in the form of hx=2 for massive particles, which is obtained from Schrodinger equation for the harmonic oscillator model. In this paper, it is shown, by the Dirac oscillator, that there is no such a zero-point energy. It is argued that when a particles wave function can spread in the whole space, it can be static. This does neither violate wave-particle duality nor uncertainty relationship. Dirac equation correctly describes physical reality, while Schrodinger equation does not when it is not the nonrelativistic approximation of Dirac equation with a certain model. The conclusion that there is no zero-point energy in the form of hx=2 is applied to solve the famous cosmological constant problem for massive particles. [ABSTRACT FROM AUTHOR]

The zero-point energies (ZPEs) of paramagnetic molecules, free and compressed in a C59N paramagnetic cage, were computed. The excess of energy acquired by molecules under compression depended on the deuterium and tritium isotopes which ranged from 6–8 kcal/mol for H2+ to 1.0–1.5 kcal/mol for HO• and HO2. The differences in the ZPEs of compressed isotopic molecules resulted in large deuterium and tritium isotope effects which differed for singlet and triplet spin states. The hyperfine coupling (HFC) constants for protons and 17O nuclei decreased under compression, confirming the leakage of the unpaired π-electron from the central oxygen atom of guest molecules into the system of π-electrons of the cage, and its distribution over 60 atoms of the C59N. The latter seems to be the reason why the nitrogen-14 HFCs for C59N remain almost unchanged upon encapsulation of guest molecules. The singlet-triplet splitting is shown to depend on the Coulomb interaction, which controls the sign of the exchange potential. The importance of compression effects on the functioning of enzymes as molecular compressing devices is discussed. [ABSTRACT FROM AUTHOR]

The classical uncertainty principle inequalities are imposed over the general relativity geodesic equation as a mathematical constraint. In this way, the uncertainty principle is reformulated in terms of proper space–time length element, Planck length and a geodesic-derived scalar, leading to a geometric expression for the uncertainty principle (GeUP). This re-formulation confirms the need for a minimum length of space–time line element in the geodesic, which depends on a Lorentz-covariant geodesic-derived scalar. In agreement with quantum gravity theories, GeUP imposes a perturbation over the background Minkowski metric unrelated to classical gravity. When applied to the Schwarzschild metric, a geodesic exclusion zone is found around the singularity where uncertainty in space-time diverged to infinity.

Advanced molecular dynamics (MD) simulation and infrared (IR) spectroscopy have been widely adopted to reveal the detailed dynamic process of high-speed selective permeability of potassium channels. Yet these MD simulations cannot avoid the choice of empirical molecular force fields and high transmembrane voltages (as driving electric fields for ions) far exceeding physiological levels. Moreover, the IR spectroscopy method usually requires isotope labels for carbonyl groups of the channels, which may change the original permeation process. Here, we build the terahertz (THz) trapped ion model for the selectivity filter (SF) of potassium channels KcsA based on the density functional theory (DFT) calculation of ion potentials. In this model, the zero-point energy of trapped ions and quantum tunneling effect provide the physical basis for near diffusion limited permeation rates of ions and explain the high driving electric field in MD simulations. Quantitative calculations of zero-point energy and tunneling probability show that the quantum effect assisted knock-on mechanism may help to realize the physiological functions of potassium channels. Furthermore, based on the trapped ion model, we calculated the ion decoherence timescale under the influence of protein environmental noise. We use the quantum optics method to describe the interaction between THz waves and the trapped ion. Then the novel THz spectroscopy approaches through the THz resonance fluorescence and the intense field non-resonant effect are presented theoretically. These are expected to be isotope label-free detective methods of the rapid ion permeation dynamics. [ABSTRACT FROM AUTHOR]

This paper presents a theoretical calculation of the vacuum energy density by summing the contributions of all quantum fields’ vacuum states, which turns out to indicate that there seems to be a missing bosonic contribution in order to match the predictions of the current cosmological models and all observational data to date. The basis for this calculation is a new Zeta function regularization method used to tame the infinities present in the improper integrals of power functions. The paper also presents a few other contributions in the area of vacuum energy.

A phenomenological model of anisotropic lattice vibrations is proposed, using a temperature‐dependent spectral cutoff and varying Debye temperatures for the vibrational normal components. The internal lattice energy, entropy and Debye–Waller B factors of non‐cubic elemental crystals are derived. The formalism developed is non‐perturbative, based on temperature‐dependent linear dispersion relations for the normal modes. The Debye temperatures of the vibrational normal components differ in anisotropic crystals; their temperature dependence and the varying spectral cutoff can be inferred from the experimental lattice heat capacity and B factors by least‐squares regression. The zero‐point internal energy of the phonons is related to the low‐temperature limits of the mean‐squared vibrational amplitudes of the lattice measured by X‐ray and γ‐ray diffraction. A specific example is discussed, the thermodynamic variables of the hexagonal close‐packed zinc structure, including the temperature evolution of the B factors of zinc. In this case, the lattice vibrations are partitioned into axial and basal normal components, which admit largely differing B factors and Debye temperatures. The second‐order B factors defining the non‐Gaussian contribution to the Debye–Waller damping factors of zinc are obtained as well. Anharmonicity of the oscillator potential and deviations from the uniform phonon frequency distribution of the Debye theory are modeled effectively by the temperature dependence of the spectral cutoff and Debye temperatures. [ABSTRACT FROM AUTHOR]

The classical uncertainty principle inequalities are imposed over the general relativity geodesic equation as a mathematical constraint. In this way, the uncertainty principle is reformulated in terms of proper space-time length element, Planck length and a geodesic-derived scalar, leading to a geometric expression for the uncertainty principle (GeUP). This re-formulation confirms the need for a minimum length of space-time line element in the geodesic, which depends on a Lorentzcovariant geodesic-derived scalar. In agreement with quantum gravity theories, GeUP imposes a perturbation over the background Minkowski metric unrelated to classical gravity. When applied to the Schwarzschild metric, a geodesic exclusion zone is found around the singularity where uncertainty in space-time diverged to infinity. [ABSTRACT FROM AUTHOR]

It has previously been shown that human very small embryonic-like (hVSEL) stem cell proliferation occurs rapidly when hVSEL stem cells in platelet rich plasma (PRP) are exposed to Strachan Ovokaitys Node Generator (SONG)-modulated laser light. The surface antigens Oct 3/4, SSEA4 and CXCR4 in the lineage negative (Lin-) compartment were assessed using flow cytometry. Of these three markers, it is known that CXCR4 may be blocked from binding to flow cytometry antibodies by its antagonist ligand, the Endogenous Peptide Inhibitor of CXCR4 (EPI-X4). In this theoretical manuscript, we focus on possible novel methods of unblocking CXCR4 by SONG-modulated laser light to make it readily available for binding by flow cytometry antibodies. We propose that the SONG-modulated red laser penetrates the minor pocket of CXCR4 and thus disrupts the hydrogen bonds and salt bridges binding CXCR4 to EPI-X4. A quantum-mechanical description of the laser interaction with the hydrogen atoms of the hydrogen bonds and salt bridges provides an atom-level illustration of the forces producing stem cell proliferation effects in vitro. This is a novel description of the mechanism of action of SONG-modulated laser light on stem cell antigens at the quantum level which may have wide implications in stem cell biology and regenerative medicine.

The quantum formula of the fluctuation dissipation theorem (FDT) was given by Callen and Welton in 1951 [1] for the case of conductors, and then expanded by Kubo in 1966 [2, 3]. The drawback of these quantum relations concerns with the appearance of a zero-point contribution, hω/2 with h the reduced Planck constant and ω the angular frequency of the considered photon, which implies a divergence of the fluctuation spectrum at increasing frequencies. This divergence is responsible for a vacuum-catastrophe, to keep the analogy with the well-known ultraviolet catastrophe of the classical black-body radiation spectrum. As a consequence, the quantum formulation of the FDT as given by Callen-Welton and Kubo introduces a Field Grand Challenge associated with the existence or less of a vacuum-fluctuations catastrophe for the energy-density spectrum. Here we propose a solution to this challenge by taking into account of the Casimir energy that, in turns, is found to be responsible for a quantum correction of the Stefan-Boltzmann law.

We investigate the Casimir effect in the systems that consist of parallel but misaligned finite-size plates from the point of view of zero-point energy. We elaborate that the zero-point energies of the radiation field in the perfect conductor systems would generate a tangential Casimir force, and explore the properties and consequences of this tangential force in various conductor systems. Thereafter, we generalize our discussion to dielectrics. After calculating the total zero-point energies of the surface modes in the multilayered systems, we show that the tangential force also exists in dielectrics. We obtain the finite-conductivity corrections to the tangential force for imperfectly conducting plates, and calculate the finite-temperature corrections to the force. The typical strength of the tangential force suggests it might be observable.

The theoretical calculations for the low-lying vibrational H atoms adsorbed on the Pt(110) surface are presented. We use the H/Pt(110) model with the conventional ultrahigh vacuum and the density functional theory to study the phonon frequency. The nature of hydrogen atoms, which were adsorbed on the four different sites of Pt(110) surface, is shown. The most stable site of the short bridge is in agreement with previous studies. The highest stretching frequency of 2200 cm−1 and the zero-point energy (ZPE) of the H atom on top site ~ 140 meV are calculated. Our results convincingly demonstrate the need to study the local oscillation to understand the dynamics of this system. [ABSTRACT FROM AUTHOR]

We give an overview of the work done during the past ten years on the Casimir interaction in electronic topological materials, our focus being solids, which possess surface or bulk electronic band structures with nontrivial topologies, which can be evinced through optical properties that are characterizable in terms of nonzero topological invariants. The examples we review are three-dimensional magnetic topological insulators, two-dimensional Chern insulators, graphene monolayers exhibiting the relativistic quantum Hall effect, and time reversal symmetry-broken Weyl semimetals, which are fascinating systems in the context of Casimir physics. Firstly, this is for the reason that they possess electromagnetic properties characterizable by axial vectors (because of time reversal symmetry breaking), and, depending on the mutual orientation of a pair of such axial vectors, two systems can experience a repulsive Casimir–Lifshitz force, even though they may be dielectrically identical. Secondly, the repulsion thus generated is potentially robust against weak disorder, as such repulsion is associated with the Hall conductivity that is topologically protected in the zero-frequency limit. Finally, the far-field low-temperature behavior of the Casimir force of such systems can provide signatures of topological quantization.

Carboxylic‐acid adsorption on anatase TiO2 is a relevant process in many technological applications. Yet, despite several decades of investigations, the acid‐proton localization—either on the molecule or on the surface—is still an open issue. By modeling the adsorption of formic acid on top of anatase(101) surfaces, we highlight the formation of a short strong hydrogen bond. In the 0 K limit, the acid‐proton behavior is ruled by quantum delocalization effects in a single potential well, while at ambient conditions, the proton undergoes a rapid classical shuttling in a shallow two‐well free‐energy profile. This picture, supported by agreement with available experiments, shows that the anatase surface acts like a protecting group for the carboxylic acid functionality. Such a new conceptual insight might help rationalize chemical processes involving carboxylic acids on oxide surfaces. [ABSTRACT FROM AUTHOR]

Materials design at atomic scale to manipulate the behavior of hydrogen is one of the key strategies to improve the hydrogen-embrittlement (HE) resistance of the materials. In the present work, tuning the energetic and kinetics of hydrogen at the Ʃ5(210)[001] GB of Ni by the alloying elements are studied using a comprehensive calculation. Firstly, the metallic elements that tend to stay at the GB are screened from 12 normally used alloying elements. It is found that as the size of the alloying element increases to 30% larger than Ni, its segregation tendency at the GB increases dramatically. The GB-segregated elements reconstruct the energy-landscape of the GB for hydrogen, significantly affecting the segregation and diffusion of hydrogen. Based on the calculations of the attempt frequency and energy barrier, we find that at room temperature the jump rate of hydrogen for the rate-determining step in the long-distance diffusion can be decreased by 5–10 orders (direction dependent), as Al, Ta, W or Zr is alloyed. Meanwhile, the pathway of the rate-limiting jump of H can be diverted in the presence of the alloying element. Thus the alloyed GB can act as an obstacle for the diffusion of hydrogen rather than a fast diffusion channel as in the case of a clean GB. The theoretical results are compared to the available experimental data. The present work provides valuable guidelines for improving the HE resistance of Ni alloys via grain boundary engineering. Image 1 • Segregation of the alloying element at Ni-GB is closely related to its atomic size. • Zero-point vibration slightly enhances the segregation of H at Ni-GB. • Rate-limiting jump for the diffusion of H at Ni-GB is figured out. • Alloyed GB can significantly retard the diffusion of H. [ABSTRACT FROM AUTHOR]

The fluctuation dissipation theorem (FDT) is the basis for a microscopic description of the interaction between electromagnetic radiation and matter. By assuming the electromagnetic radiation in thermal equilibrium and the interaction in the linear-response regime, the theorem interrelates the macroscopic spontaneous fluctuations of an observable with the kinetic coefficients that are responsible for energy dissipation in the linear response to an applied perturbation. In the quantum form provided by Callen and Welton in their pioneering paper of 1951 for the case of conductors [H. B. Callen and T. A. Welton, Irreversibility and generalized noise, Phys. Rev.83 (1951) 34], electrical noise in terms of the spectral density of voltage fluctuations, S V (ω) , detected at the terminals of a conductor was related to the real part of its impedance, Re [ Z (ω) ] , by the simple relation S V (ω) = 2 ℏ ω coth ℏ ω 2 K B T Re [ Z (ω) ] , where K B is the Boltzmann constant, T is the absolute temperature, ℏ is the reduced Planck constant and ω = 2 π f is the angular frequency. The drawbacks of this relation concern with: (i) the appearance of a zero-point contribution which implies a divergence of the spectrum at increasing frequencies; (ii) the lack of detailing the appropriate equivalent-circuit of the impedance, (iii) the neglect of the Casimir effect associated with the quantum interaction between zero-point energy and boundaries of the considered physical system; (iv) the lack of identification of the microscopic noise sources beyond the temperature model. These drawbacks do not allow to validate the relation with experiments, apart from the limiting conditions when ℏ ω ≪ K B T. By revisiting the FDT within a brief historical survey of its formulation, since the announcement of Stefan–Boltzmann law dated in the period 1879–1884, we shed new light on the existing drawbacks by providing further properties of the theorem with particular attention to problems related with the electrical noise of a two-terminals sample under equilibrium conditions. Accordingly, among others, we will discuss the duality and reciprocity properties of the theorem, the role played by different statistical ensembles, its applications to the ballistic transport-regime, to the case of vacuum and to the case of a photon gas. [ABSTRACT FROM AUTHOR]

Abstract Following on our earlier work in this area, here we examine in some detail the physical mechanism involved in the Bose–Einstein condensation process. In particular we emphasise the significance of the zero value of the chemical potential at and below the critical temperature. The molar zero-point energy (ZPE) for an ideal gas of He4 atoms in our new analysis is estimated and found to be very close to that calculated for an ideal Fermi gas of He3 atoms under the same conditions. This gives numerical support to our theory. We also show how the theory is consistent with the presence of a density maximum in liquid He4. Highlights • Study of the role of the chemical potential in Bose–Einstein condensation. • Formation of a condensate in the single particle energy state at the transition point. • Calculation of the value of the zero point energy of a mole of He4 atoms. • Similarity of this value to that of the zero point energy of a mole of He3 atoms. • Consistency of the new theory with the two-fluid model for liquid He-II. [ABSTRACT FROM AUTHOR]

Diffusion Monte Carlo (DMC) simulations have been used to obtain quantum zero‐point energies of methanol and all its isotopologs and isotopomers, using a new, accurate semi‐global potential energy surface. This potential energy surface is a precise, permutationally invariant fit to 6676 ab initio energies, obtained at the CCSD(T)‐F12b/aug‐cc‐pVDZ level of theory. Quantum zero‐point energies of deuterated methanol isotopomers are very close to each other and so a simple statistical argument can be used to estimate the populations of each isotopomer at very low‐temperatures. The DMC simulations also indicate that there is virtually zero probability for H/D exchange in the zero‐point state. © 2019 Wiley Periodicals, Inc. Diffusion Monte Carlo trajectories for indicated isotopologs and isotopomers of methanol. [ABSTRACT FROM AUTHOR]

If two parallel uncharged conductive plates placed close to each other in order micro-meters distance in a vacuum, it would appear an attractive interaction between these two plates. This interaction is theoretically explained by the difference between the vacuum energy outside the plates and the vacuum energy inside the plates. This effect is known as the "Casimir effect" by the name of theoretical physicist Hendrik Casimir, who first predicted the existence of this force. The Casimir's effect has been proved experimentally several times. In this paper, initially is given a historical context in which the theory of Casimir's effect was developed and a chronology of attempts to prove this effect experimentally. Then is calculated mathematically Casimir's force according to the procedure followed by Casimir. There is given also a short treatment of the impact of the geometric configuration on the Casimir's effect, and at the very bottom briefly are given several possible applications of the Casimir's effect on technology (especially in nanotechnology), theoretical physics, mathematics, etc. [ABSTRACT FROM AUTHOR]

An explanation of the origin of dark matter is suggested in this work. The argument is based on symmetry considerations about the concept of mass. In Wigner’s view, the rest mass and the spin of a free elementary particle in flat space-time are the two invariants that characterize the associated unitary irreducible representation of the Poincaré group. The Poincaré group has two and only two deformations with maximal symmetry. They describe respectively the de Sitter (dS) and anti-de Sitter (AdS) kinematic symmetries. Analogously to their shared flat space-time limit, two invariants, spin and energy scale for de Sitter and rest energy for anti-de Sitter, characterize the unitary irreducible representation associated with dS and AdS elementary systems, respectively. While the dS energy scale is a simple deformation of the Poincaré rest energy and so has a purely mass nature, AdS rest energy is the sum of a purely mass component and a kind of zero-point energy derived from the curvature. An analysis based on recent estimates on the chemical freeze-out temperature marking in Early Universe the phase transition quark–gluon plasma epoch to the hadron epoch supports the guess that dark matter energy might originate from an effective AdS curvature energy.

Highlights • Heat capacity of Pt(C 5 H 7 O 2) 2 molecular crystal was measured in the 239–515 K range. • Phonon density of states was calculated from low-temperature heat capacity. • Isobaric and isochoric thermodynamic functions up to the melting point were obtained. • Zero-point energy, total enthalpy and internal energy were presented. Abstract The heat capacity of Pt(C 5 H 7 O 2) 2 molecular crystal was measured in the temperature range of 239–515 K. Using data on the heat capacity, the most important thermodynamic and physical characteristics of Pt(C 5 H 7 O 2) 2 were obtained. The density of states g (ω) and characteristic temperatures related to the moments of the g(ω) were obtained. We demonstrate the possibility to calculate the molar zero-point energy from the experiment with high accuracy. The isobaric thermodynamic functions (entropy, enthalpy and reduced Gibbs energy) were calculated. Using the information about g (ω), the isochoric thermodynamic functions (heat capacity, entropy, internal energy and reduced Helmholtz energy) up to the melting point were calculated. The knowledge of zero-point energy allowed calculating the total enthalpy and total internal energy of Pt(C 5 H 7 O 2) 2. A detailed analysis of the accuracy of the obtained characteristics was provided. The approach used to obtain the important characteristics of solids is general and can be used to study a wide range of objects. [ABSTRACT FROM AUTHOR]

The noble gas atoms such as He, Ne and Ar have significantly electronic ionization values around liquid nitrogen temperature (at low temperature values). Because of this feature, the noble gases which are used for some gas detectors, and which is related certain chemical process occurring in the low temperature regions of atmosphere are encouraged to be researched. The chemical reactions subjected to these noble gas atoms have been believed to exhibit important behaviors at the same temperature values. The investigation of their quantum effects in particular energy range and the dependence on temperature of chemical reactions consisting of atom-diatom molecular systems include the subject of reaction dynamics. The title reaction has showed stable structure feature in the interaction region which is the nearest interatomic distance. For this reason, it causes to be examined of dynamic effects by depending on quantum states of initial hydrogen ion. The contributions of angular behaviors of hydrogen ion related to total angular momentum and the effects of these behaviors to reaction formations are examined via three dimensional quantum mechanical methods. [ABSTRACT FROM AUTHOR]

The work presents results of research on a set of important characteristics of the molecular crystal Al(CHO) based on experimental heat capacity data. The heat capacity was measured in the temperature range 299-432 K. The isobaric thermodynamic functions (entropy, enthalpy and reduced Gibbs energy) were calculated. The phonon density of states g( ω) was calculated using high-precision data on low-temperature heat capacity. Using the information about g( ω), the isochoric thermodynamic functions (heat capacity, entropy, internal energy and reduced Helmholtz energy) in the range 0-494 K were calculated. Molar zero-point energy, total enthalpy and internal energy of Al(CHO) were determined. The knowledge of zero-point energy is very important when considering the energy balance of the solid and can be used to investigate the stability of the crystal lattice. All obtained characteristics were evaluated for accuracy. [ABSTRACT FROM AUTHOR]