Pressure consistency for binary hard-sphere mixtures from an integral equation approach

The site-site Ornstein-Zernike equation combined with the Verlet-modified bridge function has been applied to the binary hard sphere mixtures and pressure consistency has been tested. An equation of state has been computed for the case where a packing fraction is $\eta = 0.49$, diameter ratios are $\sigma_{2}/\sigma_{1} = 0.3$ and $0.6$, and the mole fractions are $x_{1} = 0.125, 0.5, 0.75$, and $1$. An excess chemical potential for each component has been obtained as well. Our findings for thermodynamic properties are in good agreement with available data in literature.Comment: 9 page

Calculation of the entropy for hard-sphere from integral equation method

The Ornstein-Zernike integral equation method has been employed for a single-component hard sphere fluid in terms of the Percus-Yevick (PY) and Martynov-Sarkisov (MS) approximations. Virial equation of state has been computed in both approximations. An excess chemical potential has been calculated with an analytical expression based on correlation functions, and the entropy has been computed with a thermodynamic relation. Calculations have been carried out for a reduced densities of 0.1 to 0.9. It has been shown that the MS approximation gives better values than those from the PY approximation, especially for high densities and presents a reasonable comparison with available data in the literature.Comment: 7 page

Equilibrium thermodynamic properties of binary hard-sphere mixtures from integral equation theory

We present an equilibrium thermodynamic properties of binary hard-sphere mixtures from integral equation approach combined with the Percus-Yevick (PY) and the Martynov-Sarkisov (MS) approximations. We use the virial, the compressibility and the Boubl\'{i}k-Mansoori-Carnahan-Starling-Leland (BMCSL) equations of state in the PY approximation, while the virial equation of state is only employed in the MS approximation. We employ a closed-form expression for evaluating the excess chemical potential. The excess Helmholtz free energy is obtained using the Euler relation of thermodynamics. For a number of binary sets of the mixtures we compare our findings for thermodynamic properties with previously obtained results in the literature. Generally, the findings from the MS approximation show better agreement with the results than those from the PY approximation.Comment: 10 pages, 6 figure

Recent Approaches for Chemical Speciation and Analysis by Electrospray Ionization (ESI) Mass Spectrometry

In recent years, the chemical speciation of several species has been increasingly monitored and investigated, employing electrospray ionization mass spectrometry (ESI-MS). This soft ionization technique gently desolvates weak metal\u2013ligand complexes, taking them in the high vacuum sectors of mass spectrometric instrumentation. It is, thus, possible to collect information on their structure, energetics, and fragmentation pathways. For this reason, this technique is frequently chosen in a synergistic approach to investigate competitive ligand exchange-adsorption otherwise analyzed by cathodic stripping voltammetry (CLE-ACSV). ESI-MS analyses require a careful experimental design as measurement may face instrumental artifacts such as ESI adduct formation, fragmentation, and sometimes reduction reactions. Furthermore, ESI source differences of ionization efficiencies among the detected species can be misleading. In this mini-review are collected and critically reported the most recent approaches adopted to mitigate or eliminate these limitations and to show the potential of this analytical technique

A method for accurate electron-atom resonances: The complex-scaled multiconfigurational spin-tensor electron propagator method for the ^2P\, \mbox{Be}^{-} shape resonance problem

We propose and develop the complex scaled multiconfigurational spin-tensor electron propagator (CMCSTEP) technique for theoretical determination of resonance parameters with electron-atom/molecule systems including open-shell and highly correlated atoms and molecules. The multiconfigurational spin-tensor electron propagator method (MCSTEP) developed and implemented by Yeager his coworkers in real space gives very accurate and reliable ionization potentials and attachment energies. The CMCSTEP method uses a complex scaled multiconfigurational self-consistent field (CMCSCF) state as an initial state along with a dilated Hamiltonian where all of the electronic coordinates are scaled by a complex factor. CMCSCF was developed and applied successfully to resonance problems earlier. We apply the CMCSTEP method to get ^2 P\,\mbox{Be}^{-} shape resonance parameters using $14s11p5d$, $14s14p2d$, and $14s14p5d$ basis sets with a $2s2p3d$\,CAS. The obtained value of the resonance parameters are compared to previous results. This is the first time CMCSTEP has been developed and used for a resonance problem. It will be among the most accurate and reliable techniques. Vertical ionization potentials and attachment energies in real space are typically within $\pm 0.2\,eV$ or better of excellent experiments and full configuration interaction calculations with a good basis set. We expect the same sort of agreement in complex space.Comment: 13 pages, 3 figue

Numerical solution to the time-dependent Gross-Pitaevskii equation

We solve the time-dependent Gross-Pitaevskii equation modeling the dynamics of the Bose-Einstein condensate trapped in one-dimensional and two-dimensional harmonic potentials using the split-step technique combined with a pseudospectral representation. We apply this method to the simulation of condensate breathing when an inter-particle interaction in the system is not too strong.Comment: 11 pages, 8 figure

Photoionization from the ground and excited vibrational states of H+2 and its deuterated isotopologues

Photoionization cross sections and rate coefficients have been calculated for all bound vibrational levels of the 1s$\sigma_{\mathrm{g}}$ state of H$_{2}^{+}$, HD$^{+}$, and D$_{2}^{+}$. The Born-Oppenheimer approximation is employed in our calculation of vibrationally-resolved photoionization cross sections. Vibrationally-resolved and local thermal equilibrium photoionization rate coefficients are presented for photon temperatures less than $50\,000$ K and are found to be several orders of magnitude larger than previous results in the literature. Analytic fits for the vibrationally-resolved and local thermal equilibrium photoionization rate coefficients are provided. Near threshold oscillations in the vibrationall-resolved photoionization are observed. A benchmark set of photoionization cross sections are presented. Fixed-nuclei photoionization cross sections are calculated using two-center true continuum wave functions and are verified by comparison with previous calculations and are found to be in excellent agreement in all cases. Data files for our set of benchmark cross sections, rate coefficients, and fitting parameters for H$_{2}^{+}$, HD$^{+}$, and D$_{2}^{+}$ are available on Zenodo under an open-source Creative Commons Attribution license: https://doi.org/10.5281/zenodo.8304060 .Comment: Accepted in ApJ