A new six-dimensional potential energy surface for H2–N2O and its adiabatic-hindered-rotor treatment

Abstract

A six-dimensional ab initio potential energy surface (PES) for H2-N2O which explicitly includes the symmetric and asymmetric vibrational coordinates Q1 and Q3 of N2O is calculated at the coupled-cluster singles and doubles with noniterative inclusion of connected triple level using an augmented correlation-consistent polarized-valence quadruple-zeta basis set together with midpoint bond functions. Four-dimensional intermolecular PESs are then obtained by fitting the vibrationally averaged interactions energies for υ3(N2O) = 0 and 1 to the Morse∕long-range analytical form. In the fits, fixing the long-range parameters at theoretical values smoothes over the numerical noise in the ab initio points in the long-range region of the potential. Using the adiabatic hindered-rotor approximation, two-dimensional PESs for hydrogen-N2O complexes with different isotopomers of hydrogen are generated by averaging the 4D PES over the rotation of the hydrogen molecule within the complex. The band-origin shifts for the hydrogen-N2O dimers calculated using both the 4D PESs and the angle-averaged 2D PESs are all in good agreement with each other and with the available experimental observations. The predicted infrared transition frequencies for para-H2-N2O and ortho-D2-N2O are also consistent with the observed spectra.

Analytic Morse/long-range potential energy surfaces and predicted infrared spectra for CO–H2 dimer and frequency shifts of CO in (para-H2)N N = 1–20 clusters

“…In similar way, clusters of para-hydrogen (para H 2 ) molecules doped with a single chromophore molecule [22][23][24][25][26][27][28][29][30][31][32][33] are also considered as a possible route to investigate the superfluidity of para-hydrogen. Recently, combining experimental measurements and theoretical simulations, the non-classical rotational inertia and superfluid response in pure para H 2 clusters doped with CO 2 have been first elucidated.…”

Analytic potentials and vibrational energies for Li$_{2}$ states dissociating to $\mbox{Li}\left(2S\right)+\mbox{Li}\left(3P\right)$. Part 1: The $^{2S+1}Π_{u/g}$ states

“…MLR-type potentials have successfully described spectroscopic data for many electronic states of many diatomic molecules [11, 12, 16-18, 31, 48, 55-72]. It has also become customary to fit ab initio data for diatomic [73][74][75][76][77][78][79] and polyatomic [66,[80][81][82][83][84] systems to MLR models . Therefore, we use the MLR model in this study, and the results here support the idea of the MLR model being a strong candidate for a "universal" model for potential energy curves and surfaces.…”

State of the art for ab initio vs empirical potentials for predicting 6e$^{-}$ excited state molecular energies: Application to Li$_{2}\left(b,1^{3}Π_{u}\right)$

“…Having this long-range physics accurately built into the model is almost as helpful as having data in the long-range region, as was the case of the c-state. MLR-type empirical potentials have now successfully described spectroscopic data for many diatomic [2,3,5,17,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] and polyatomic [48,[56][57][58][59][60] systems. Therefore, we will proceed to use the MLR model to describe V BO (r).…”