Energies of dipole-bound anionic states

Abstract

Ž. Dipole-bound anionic states of CH CN, C H , and HF were studied using highly 3 3 2 2 correlated electronic structure methods and extended one-electron basis sets. The electron detachment energies were calculated using the coupled cluster method with single, double, and noniterative triple excitations. Geometrical relaxation of the molecular framework upon electron attachment and the difference in the harmonic zero-point vibrational energies between the neutral and the dipole-bound anionic species were calculated at the MP2 level of theory. We demonstrate that the dispersion interaction between the loosely bound electron and the electrons of the neutral molecule is an important component of the electron binding energy, comparable in magnitude to the electrostatic electrondipole stabilization. The geometrical relaxation upon electron attachment and the change in the zero-point vibrational energy is important for the weakly bound HF dimer. The predicted values of the vertical electron detachment energies for the dipole bound states of CH CN and C H of 112 and 188 cm y1 , 3 3 2 respectively, are in excellent agreement with the recent experimental results of 93 and y1 Ž. y 171 " 50 cm , respectively. For HF , the predicted value of adiabatic electron 2 detachment energy is 396 cm y1 , whereas the experimental vertical detachment energy is 508 " 24 cm y1. The possibility of formation of the neutral dimer in an excited vibrational state is considered.

Dipole-Bound Anion of the HNNH3 Isomer of Hydrazine. An Ab Initio Study

“…This stabilizing effect, caused by quantum mechanical charge fluctuations, is similar in magnitude to E bind KT , see Table 3. This finding is consistent with our earlier results for other dipole-bound anions 26,[31][32][33][34][35][36][37] and has important implications for designing model potentials to describe dipolebound anions and solvated electrons. 62,63 The value of ∆E bind MP2-disp increases from 370 cm -1 at the optimal geometry of the neutral to 382 cm -1 at the optimal geometry of the anion.…”

“…In fact, in many cases the electron binding energy of the dipole-bound anion has been dominated by the contribution from electron correlation. 26,[31][32][33][34][35][36][37][38] The very recent studies on dipole-bound anions of hydrogen-bonded clusters 39-41 and CH 3 NO 2 42 yielded similar conclusions.…”

“…Furthermore, we found that effects beyond the second-order Møller-Plesset (MP2) level can contribute substantially to the stability of dipole-bound anionic states and solvated electrons. 26,[31][32][33][34][35][36][37] Probably the most spectacular cases in which correlation is important involve the dipole-bound anions of water-ammonia and HPPH 3 , where we found that electron correlation contributes respectively 77 and 82% to the electron binding energy. 26,36 In the present paper, we explore the role of electron correlation effects in electron binding to HNNH 3 .…”

First Evidence of Rhombic (NaCl)2‐. Ab initio Reexamination of the Sodium Chloride Dimer Anion.

“…The binding of electrons to polar molecules has been addressed in many theoretical studies. [17][18][19][20][21][22][23][24][25][26][27][28][29][30] It has been shown that, within the Born-Oppenheimer (BO) approximation, species with a dipole moment greater than 1.625 D possess an infinite number of bound anionic states. 31,32 However, a more practical critical value to experimentally observe a dipole-bound state (DBS) of anion bound by at least 1 cm -1 was found to be slightly larger, ca.…”

“…In particular, the dispersion interaction of the excess electron with the electrons of the neutral parent molecule proved to be crucial for the stability of the dipole-bound anion 18,19,[21][22][23][24] although higher-order correlation effects can also be significant. [21][22][23][24]29,35 An excess electron may be trapped inside a molecular cluster instead of being attached to the dipole moment of the neutral cluster. The existence of such species, very often referred to as solVated electrons (SE), has been known since 1864 when they were observed in liquid ammonia.…”