HCl Van Der Waals Complex Research Articles

Calculation of the Transport and Relaxation Properties of the Ar···HCl van der Waals Complex Using a New Potential Energy Surface: Comparison of the Classical and Full Quantum Mechanical Kinetic Theory Results with Molecular Dynamics Simulations.

The intermolecular potential energy surface (PES) of the Ar···HCl complex was calculated at the RCCSD(T)/aug-cc-pvQz-BF level of theory. The obtained potential was expanded in terms of Legendre polynomials and fitted to a mathematical model. The fitting results are highly correlated with the ab initio PES data with SD = 5.9 × 10-3 cm-1 and average absolute deviation (AAD) = 4.0 × 10-6 cm-1. The interaction second virial coefficients (B12) in the temperature range of 190-480 K were calculated by considering classical and first quantum corrections and compared with the available experimental data. A reasonable agreement with the experimental and calculated B12 was obtained. The PES was also used to obtain the rovibrational energy levels, and the spectroscopic rovibrational constants were obtained. It was found that the D0 values differ ∼2.25 cm-1 from the experimental values of the ground rovibrational state. Furthermore, the obtained potential was used to calculate the transport and relaxation properties using full quantum close-coupling (CC) formalism and the classical kinetic theory methods based on the Mason-Monchik approximation (MMA). It was found that the deviation between MMA and CC calculations is increased with increasing the temperature due to the higher influence of the rotational degrees of freedom on the transport properties. Also, the contribution of the inelastic (off-diagonal) transitions for diffusion coefficient is higher than the viscosity. Furthermore, the classical molecular dynamics simulations were performed using LJ(12,6) and Vashishta models, to calculate the interaction diffusion and viscosity coefficients, and compared with the results of the full quantum CC calculations. The obtained results confirm that the Vashishta model is better fitted to the ab initio potentials and is more accurate than LJ(12,6) in calculation of the diffusion coefficients.

Ab initio characterization of the Ca–HCl van der Waals complex

The equilibrium structure and three-dimensional potential energy surface of the Ca-HCl van der Waals complex in its ground electronic state have been determined from accurate ab initio calculations using the coupled-cluster method, CCSD(T), in conjunction with basis sets of quadruple- and quintuple-zeta quality. The core-electron correlation, high-order valence-electron correlation, and scalar relativistic effects were investigated. The Ca-HCl complex was confirmed to be linear at equilibrium, with the vibrationless dissociation energy (into Ca and HCl) D(e) of 287 cm(-1). The vibration-rotation energy levels of various Ca-HCl isotopomers were predicted using the variational method. The predicted spectroscopic constants can be useful in a further analysis of high-resolution vibration-rotation spectra of the Ca-HCl complex.

Accurate intermolecular ground state potential of the He–HCl van der Waals complex

We evaluate the rovibrational spectrum of the He–HCl van der Waals complex from an accurate ground state intermolecular potential, obtained from CCSD(T) interaction energies. After a systematic basis set study, we select the aug-cc-pV5Z basis set extended with midbond functions. The potential is characterized by two linear minima, i.e., He–ClH and He–HCl, with distances from the He atom to the HCl centre of mass of 3.349 and 3.832 Å, respectively; and energies of −32.74 and −31.16 cm −1, respectively. The rovibrational spectra for the different isotopic species are calculated. The results are compared to those previously available.

Bound States of the Cl(2P)−HCl van der Waals Complex from Coupled ab Initio Potential Energy Surfaces

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionORIGINAL ARTICLEThis notice is a correctionBound States of the Cl(2P)−HCl van der Waals Complex from Coupled ab Initio Potential Energy SurfacesW. B. Zeimen, J. Kłos, G. C. Groenenboom, and A. van der AvoirdCite this: J. Phys. Chem. A 2004, 108, 42, 9319–9322Publication Date (Web):September 21, 2004Publication History Published online21 September 2004Published inissue 1 October 2004https://doi.org/10.1021/jp046260aCopyright © 2004 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views192Altmetric-Citations9LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (187 KB) Get e-Alerts Get e-Alerts

Bound States of the Cl(2P)−HCl van der Waals Complex from Coupled ab Initio Potential Energy Surfaces

With the use of recently computed diabatic potential energy surfaces (J. Chem. Phys. 2001, 115, 3085) a full ab initio calculation was made of the bound energy levels of the Cl(2P)−HCl van der Waals complex for total angular momentum J = 1/2, 3/2, 5/2, and 7/2. The dissociation energy D0 of the complex was found to be 337.8 cm-1 for J = 1/2 and |Ω| = 1/2, where Ω is the projection of J on the Cl−HCl bond axis. The complex is T-shaped in the ground state and in a series of stretch and bending excited states, with a van der Waals bond length R of ∼3.2 Å. A series of states with linear geometry were also found, however, with |Ω| = 3/2 and R ≈ 3.9 Å, the lowest of which has a binding energy of 276.1 cm-1. The rovibronic levels were analyzed with the help of one-dimensional calculations with R fixed at values ranging from 2.5 to 5.5 Å and the use of diabatic and adiabatic potential energy surfaces that both include the important spin−orbit coupling. The states of linear geometry are in qualitative agreement with previous work based on more approximate potential energy surfaces; the T-shaped states of considerably lower energy were not predicted earlier. Analysis of the rotational structure and parity splitting of the rovibronic levels leads to the remarkable observation that this T-shaped complex shows several features typical of a linear open-shell molecule.

Electronic structure of Ne–H–Cl and Ne–Cl–H using the G1, G2 and MP4 methods

The potential energy surface for the Ne–HCl Van der Waals complex is calculated using fourth-order Møller–Plesset perturbation theory (MP4) employing both 6-311G **, cc-pVDZ and AUG-cc-pVDZ basis sets. The global minimum occurs at the linear Ne–H–Cl configuration. The binding energy of the linear Ne–H–Cl and Ne–Cl–H configurations has also been calculated using G1, G2 and MP4 methods. The G1 and G2 methods cannot predict the relative stability of the complexes, since the difference in the calculated binding energies is small. In all the calculations, the binding energy of the Ne–H–Cl and Ne–Cl–H complex is low compared to that of the Ar–HCl Van der Waals complex for which D e=2.096 kJ/mol.

On the angular geometry of the CH 3Cl · HCl van der Waals complex in the gas phase and in liquefied noble gas solutions

The equilibrium geometry, relative stability and vibrational frequencies of CH 3Cl · HCl were calculated using MP2/6-31+G ∗∗ ab initio calculations. The results are discussed in the light of the infrared spectroscopic study of CD 3Cl/HCl mixtures, dissolved in liquefied noble gases. The influence of the solvents on the properties of the complex was investigated using the reaction field model, at the RHF/6-311+G ∗∗ level.

Resonances in the UV photodissociation of the Ar…HCl van der Waals complex? An exact quantum 3D wave packet study

We investigate the ‘one-atom cage effect’ in the ultraviolet photodissociation of HCl in the Ar…HCl van der Waals complex, in particular the possibility of resonance structures caused by trapping of the hydrogen atom between its heavy partners Ar and Cl. The dynamics are treated by solving exactly the time-dependent Schrödinger equation using the usual Jacobi coordinates for a triatomic molecule. The kinetic energy distribution of the H atom and the absorption spectrum are both completely structureless, demonstrating that trapping of hydrogen is negligibly small and ruling out the cage effect in Ar…HCl.

Resonances in the photodissociation of HCl in the Ar–HCl van der Waals complex: How prominent are they?

We investigate the cage effect in the ultraviolet (UV) photodissociation of the Ar...HCl van der Waals complex, especially the possibility of resonance structures caused by trapping of the hydrogen atom between its heavy partners as recently highlighted by Garcia-Vela and Gerber [J. Chem. Phys. 98, 427 (1993)]. The dynamics is described by solving the time-dependent Schrödinger equation employing the standard Jacobi coordinates which are routinely used for triatomic systems. Due to the large size of the required grid, exact three-dimensional (3D) wave packet calculations are extremely time consuming and could be followed up to 20 fs only. This time is sufficient for calculating the absorption spectrum, but too short for determining the final kinetic energy distributions of the fragment atoms. Therefore, the photodissociation dynamics is mainly treated in a vibrationally sudden approximation, in which the dynamical calculations are performed for a range of fixed ArCl bond distances, and the results averaged over this bond length. 3D classical trajectory calculations show that the energy transfer out of the dissociative HCl mode is very weak (∼5% of the total energy), supporting the application of the sudden approximation. In this approximation, both the absorption spectrum and the kinetic energy distribution associated with the dissociating HCl motion exhibit very weak diffuse structures (resonances) which, following the work of Garcia-Vela and Gerber, can be assigned to the transient vibrational motion of hydrogen between Ar and Cl. However, in our calculations these structures are much less pronounced than in the work of Garcia-Vela and Gerber. The very small amplitudes of the resonance features indicate that trapping in the dissociation of HCl in Ar...HCl is marginal, and much less important than suggested by the previous studies of Garcia-Vela et al. Furthermore, in contrast to the work reported by Garcia-Vela et al., we do not find any evidence for the narrow, irregular features superimposed on the resonance structures.

Determination of the bound and quasibound states of Ar–HCl van der Waals complex: Discrete variable representation method

The ArHCl (HCl; ν=0) van der Waals (vdW) molecule has a large number of bound and rotationally predissociative (resonance) states for total angular momentum in the range of 0≤J≤60. Using the Jacobi coordinates and the total angular momentum representation in the body-fixed reference frame, the Hamiltonian is evaluated in the discrete variable representation (DVR) of the stretch and bend internal vibrational basis and a basis of parity adapted rotation functions. The facile and effective application of the DVR is greatly enhanced by an appropriate choice of the basis set. The sequential diagonalization and truncation of the Hamiltonian permit accurate and efficient determination of eigenstates. Using Hutson’s H6 potential energy surface, the energies and wave functions of all bound and resonance states are computed for selected J’s up to J=60. A novel flux projection technique facilitates semiquantitative evaluation of the lifetimes of all states and, in particular, the simple identification of the resonance states in the ℒ 2 eigenvector basis.

The intermolecular potential of Ne–HCl: Determination from high-resolution spectroscopy

A new intermolecular potential for Ne–HCl with HCl in its v=1 state is obtained by least-squares fitting to molecular-beam near-infrared laser spectra of the Ne–HCl and Ne–DCl van der Waals complexes. In agreement with previous potentials, the equilibrium geometry is found to be linear Ne–H–Cl, with a well depth around 64 cm−1. There is also a secondary minimum at the linear Ne–Cl–H geometry, with a depth around 57 cm−1, which arises because the Ne atom can approach closer to the Cl atom at the linear geometry than at a T-shaped geometry. The new potential is slightly less anisotropic than earlier potentials for HCl in its v=0 state. The fitted potential is used to calculate additional bound states of the Ne–HCl van der Waals complex, which have not yet been observed spectroscopically.

The intermolecular potential of Ar–HCl: Determination from high-resolution spectroscopy

Two new intermolecular potentials for Ar–HCl are obtained by least-squares fitting to molecular beam microwave and far-infrared laser spectra of the Ar–HCl van der Waals complex. In agreement with previous potentials, the equilibrium geometry is found to be linear Ar–H–Cl, with a well depth around 175 cm−1. However, the far-infrared spectra allow the potential in the region of the linear Ar–Cl–H geometry to be determined as well, and a secondary minimum is found at this geometry, with a depth around 140 cm−1. The secondary minimum arises because the Ar atom can approach closer to the Cl atom at the linear geometry than at a T-shaped geometry. The fitted potential is used to calculate additional bound states of the Ar–HCl van der Waals complex, which have not yet been observed spectroscopically.

A photoionization study of the van der Waals molecule C2H4 � HCl

The dissociation energy of the C2H4 · HCl van der Waals complex was determined to be 3.18±0.73 kcal mol−1 by a dissociative photoionization technique. C2H4 · HCl was produced by free expansion of a 1:4 mixture of C2H4 in HCl and the clusters were ionized with tunable synchrotron radiation. The photoionization efficiency function of (C2H4 · HCl)+ from C2H4 · HCl was determined between 600 and 1,300 A and the onset for (C2H4 · HCl)+ was established as 1,163±2 A = 10.66±0.02 eV; these values give ΔHf0(C2H4 · HCl) = −10.7±0.7 kcal mol−1 and ΔHf0(C2H4·HCl+)=235.1±0.9 kcal mol−1. A complex ion dissociation energyD0(C2H4 · HCl+) = −0.3±0.9 kcal mol−1 was calculated from the results. The major features on the PIE curve for C2H4 · HCl+ can be analyzed in terms of the known energetic features of C2H4+ and HCl. An extended energy diagram for the C2H4 + HCl system is presented.

Rotational predissociation and libration in the infrared spectrum of ArHCl

Fully resolved rotational structure in the high-frequency vibrational region of the ArHCl van der Waals complex has been recorded under thermal equilibrium conditions at T=127 K with a tunable difference-frequency laser. Both the fundamental HCl stretch and its combination with the low-frequency large-amplitude bend (libration) have been observed with comparable intensities. An abrupt cutoff of the spectrum at high J due to rotational predissociation yields a measure of the binding energy of the complex. The band centre shifts and rotational and distortion constants provide much information about the interaction potential surface and its vibrational dependence and about perturbations from other low-frequency modes not directly observed.

Rotational predissociation of the Ar⋅HCl van der Waals complex: Close-coupled scattering calculations

We report an extensive computational study of rotationally predissociating metastable states of the Ar⋅HCl van der Waals complex, using a highly realistic empirical intermolecular potential recently proposed by Hutson and Howard. The states are characterized by fully converged, close-coupled, scattering calculations. Resonance energies, widths, and partial widths are extracted by fitting the energy dependence of S matrices. Total angular momenta of 0 and 1 are studied, and the calculations span an energy range from 0 to 1400 cm−1. The resonance widths vary from <10−4 to ≳5 cm−1, and it is shown that the isolated narrow resonance approximation is of poor validity for the wider resonances. Comparison of the close-coupling results with approximate calculations enables assignment of approximate quantum numbers to the metastable states. Physical explanations are suggested for the strong trends in resonance parameters as a function of the intermolecular stretching, diatom rotation, and molecule-fixed angular momentum projection quantum numbers. A changeover from a near-molecule-fixed to a near-space-fixed coupling scheme, as angular momentum is increased, is clearly demonstrated. The results are of considerable relevance to the design of experiments and the development of approximate computational methods in this area.

Exact calculation of the rotational–vibrational energy levels of triatomic species

A recently proposed method for calculating the bound rotational-vibrational energy levels of triatomic molecules is applied to the Ar—HCl van der Waals complex and to the water molecule. For Ar—HCl energy levels, rotational constants and centrifugal distortion constants for several different potential-energy functions are calculated. The accuracy of the calculations is critically examined and is found to be very high. It is demonstrated that the method may be used to calculate the higher lying rotational–vibrational energy levels of the complex without either a significant loss of accuracy or any large increase in computational effort. The complete set of rotational–vibrational energy levels is calculated for two different Ar—HCl potentials and for several different values of the total angular momentum. The coupled states or p-helicity decoupling approximation, which has been used previously in the context of molecular scattering theory, is examined and shown to yield very reliable results. This approximation greatly reduces the computational effort required to perform calculations, especially for higher values of the total angular momentum. In the case of the water molecule we examine the use of a “hindered-rotor” basis set, and show that we are able to obtain a faster rate of convergence and greater accuracy for the low-lying energy levels of water with this type of basis.

ArHCl interaction potential from differential elastic scattering cross section measurements

The crossed molecular beam technique has been used to determine the ArHCl spherically symmetric potential. Analysis of the data obtained at a relative collision energy of 12.4 × 10 −14 erg (1.78 kcal mole −1) yields a potential with ϵ/ k = 191°K, r m = 4.0 Å. These results are shown to be in agreement with other experimental conclusions on the ArHCl van der Waals complex as well as with transport phenomena.