Exchange interaction between two different atoms at large distances

Different cases of the exchange interaction in the system (A+e+C⁺) are considered and corresponding expressions for this interaction are obtained. A suitable representation for the electron atom interaction is also discussed.     

Exchange interaction energy between two one-active electron atoms at large distances

Developed formulas for the exchange interaction energy between two neutral one-active electron atoms interacting at large distances R are presented in terms of known basic integrals obtained from an asymptotic method for the alkali dimers M₂ dissociating to M(ns) + M(ns), M(n′l) + M(n′l), l = 0, …, 3 and M (np) + M(np). Detailed illustrative numerical results are displayed for the molecular states of Na₂ dissociating to the limit Na(3s) + Na(3p). Comparisons with very accurate ab initio results as well as with some available experimental data show that accurate potential energy curves for these excited states may be obtained in a very large range of internuclear distances by connecting ab initio curves for small and intermediate values of R with long-range curves obtained as the sum of usual multipolar Coulombic energy and asymptotic exchange energy.     

Long-range interaction between 1s and 2s or 2p hydrogen atoms

Long-range interaction energy between two hydrogen atoms has been computed in the second order of the perturbation theory. All states of the system arising when one of the atoms is in the 1s and the other in the 2s or 2p state have been considered. The energy represented by a series expansion in inverse powers of the internuclear distance, R, has been computed up to the terms in R^?8. The results are believed to give reliable interaction energies for R > 15 a.u. Accurate interaction energy for two ground-state hydrogen atoms has also been obtained up to the terms in R^?10. Results for the B′ ¹∑ state are employed to discuss the experimental ground-state dissociation energy of H₂, D₂, and HD. For H₂ all values of the dissociation energy obtained from various experimental absorption limits, by using the computed potential energy curve to separate off the effect of rotation, are shown to be satisfactorily consistent. The resulting total energy of H₂ is, however, higher than the most accurate theoretical value.     

Dispersion interaction between helium atoms

Accurate values for the coefficients of the R^?6, R^?8 and R^?10 in the series representation of the dispersion interaction between two helium atoms at distance R are obtained by a simple variation method.     

Fourth-order diagrammatic MB-RSPT calculations of the interaction energy between two helium atoms

The efficiency of the MB-RSPT in the calculations of the correlation contributions to the interaction energies was investigated, using He₂ as a model Van der Waals system. The attention has been focused on the convergency of the perturbation expansion in the calculations of the interaction energy and on the analysis of the fourth-order terms of MB-RSPT. The rôle of the renormalization term in the correct long-range behaviour of the interaction potential has been emphasized.     

Mechanism of the formation of hydrogen tetroxide and peroxide via low-temperature interaction between hydrogen atoms and molecular oxygen

A mechanism and kinetic model for the synthesis of peroxide radical condensate via the low-temperature interaction of hydrogen atoms with O₂ molecules is proposed. The main components of the reaction, hydrogen tetroxide H₂O₄ and hydrogen peroxide H₂O₂, are formed in a low-temperature liquid layer formed near the cold surface during synthesis. Molecules of H₂O₄ and H₂O₂ are stabilized by transitioning to the solid phase. The dependences of the \(N_{O_2 } /N_{H_2 O_2 }\) ratio on the ratio of concentrations of H and O₂ in the gas phase, calculated on the basis of the model, are consistent with the experimental data.     

The interaction curve of non-bonded carbon and hydrogen atoms and its application

A universal interaction curve of non-bonded carbon and hydrogen atoms has been proposed. This curve has been successfully applied to determine numerous properties of various saturated and unsaturated hydrocarbons such as the equilibrium of molecular conformation, the strain energy of molecules, the sublimation heat of organic crystals and so on.     

A simple model of short-range interactions II. The orientation dependence of the interaction between non-bonded hydrogen atoms

The simple model of short-range interactions described in the preceding paper has been applied to the study of the orientation dependence of the interaction between the non-bonded hydrogen atoms of two CH fragments. Calculation shows that for the same interatomic distance the interaction energy between non-bonded hydrogen atoms is strongly dependent on the relative orientation of the two bonds even for large values ofR.     

两个氢、氮、氧或氯原子间的Van der Waals能

根据气体的VanderWaals常数和两个氢原子间的VanderWaals能之理论值,计算了两个氢、氮、氧或氯原子间的VanderWaals能。     

The role of chemisorption in the interaction of nitrous oxide with free hydrogen atoms

Conclusions The first, chemisorbed monomolecular layer of N₂O is the site of the most intense reaction between gaseous atomic hydrogen and nitrous oxide adsorbed on platinum.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 507–510, March, 1979.     

The interaction of directional lone pairs between bonded atoms: Hydrazine

The directional components of the barrier to rotation in hydrazine are investigated. The repulsion of the lone pairs appears to be significant, favoring the form with perpendicular lone pairs over the syn and anti forms.[/p]     

New insights into the interaction of hydrogen atoms with boron-substituted carbon

Boron substitution in carbon materials has been comprehensively investigated using the density functional theory method. It was found that there is a correlation between the stability of the graphene sheet, the distribution of pi electrons, the electrostatic potential, and the capability for hydrogen-atom adsorption. Boron substitution destabilizes the graphene structure, increases the density of the electron wave around the substitutional boron atoms, and lowers the electrostatic potential, thus improving the hydrogen adsorption energy on carbon. However, this improvement is only ca. 10-20% instead of a factor of 4 or 5. Our calculations also show that two substitutional boron atoms provide consistent and reliable results, but one substitutional boron results in contradictory conclusions. This is a warning to other computational chemists who work on boron substitution that the conclusion from one substitutional boron might not be reliable.     

The interaction of metastable helium atoms with alkali atoms

Using crossed beams of ground state alkali atoms A (A = Li, Na, K, Rb, Cs) and metastable He(2³ S), He(2¹ S) atoms, we have measured the energy spectra of electrons resulting in the respective Penning ionization processes at: thermal collision energies. The data are interpreted to yield the well depthD _e ^* of the²Σ interaction potentials as follows: He(2³ S)+A:D _e ^* (A=Li)=868(20) meV;D _e ^* (Na)=740(25) meV;D _e ^* (K)=591(24) meV;D _e ^* (Rb)=546(18) meV;D _e ^* (Cs)=533(18) meV. He(2¹ S)+A:D _e ^* (Li)=330(17) meV;D _e ^* (Na)=277(24) meV;D _e ^* (K)=202(23) meV;D _e ^* (Rb)=219(18) meV;D _e ^* (Cs)=277(18) meV. The well depth for He(2³ S)+A(²Σ) is always close to 80% of the well depth for Li(2s)+A(X ¹Σ). The ionization cross sections for He(2¹ S)+A are about 3 to 4 times larger than those for He(2³ S)+A.     

Long- and intermediate-range interaction between hydrogen atoms in the B 1Σ state

The energy of the hydrogen molecule in the B ¹Σ state, for internuclear separations 12 ≦ R ≦ 20 a.u., has been computed using an 80-term variational wave function depending explicitly on the interelectronic distance. The same type of wave function has been employed in the perturbation theory approach. Using the polarization approximation, and not expanding the interaction Hamiltonian, the first-, second- and third-order energies have been computed and higher-order corrections have been estimated. The results show that in the region under consideration E and E represent the dominant contributions to the interaction energy in the B state.     

Ab initio Hartree–Fock and configuration-interaction treatment of the interaction between two nickel atoms

The interaction between two nickel atoms in the configurations (3d)⁸(4s)² and (3d)⁹ (4s)¹ has been calculated using ab initio methods (Hartree–Fock and configuration interaction). The results of the calculations compare favorably with the optical spectrum. The discrepancy between the calculated and the experimental dissociation energy is discussed, and a new estimate of the dissociation energy is given. The configuration-interaction calculations show that the interaction between the two nickel atoms is of a very complex nature. In spite of this the binding can be interpreted in a simple way. The bond is minly due to the 4sσ_g molecular orbital while the 3d orbitals of the two nuclei are exchange coupled.