On the theoretical side, due to its spectroscopic importance, a variety of H 3 + PESs have been developed over the years -with the latest two published only very recently. Thus far, the number of validated, and therefore recommended, experimental quality ro-vibrational energy levels of H 3 + are 652, of which 259 belong to ortho- H 3 + ( I = 3/2) and 393 to para- H 3 + ( I = 1/2), with I being the quantum number of the total nuclear spin of the system. A MARVEL analysis was also carried out for two isotopologues, H 2D + and D 2H +, with the database last updated in 2019. The resultant energy levels and assignments replaced the earlier work of. #Quantum physics calculator code#In particular, the MARVEL code (Measured Active Rotational–Vibrational Energy Levels), has been applied to ro-vibrational spectroscopic data of H 3 + that were collected from 26 separate experimental sources. Although symmetry and selection rules help, extracting the latter from the former remains a challenge, and has traditionally been something of a “black art.” Recently, more systematic approaches have been developed, based on graph theory and “spectroscopic networks” (SNs), in which the vertices represent rovibrational energy levels, and the lines represent experimentally observed spectroscopic transitions, to extract empirical energy levels directly from experimental data, with well-defined and realistic uncertainties. Of course, the primary challenge with respect to labeling is that experiments provide only spectroscopic transitions, not the ro-vibrational energy levels themselves. On the experimental side, numerous spectroscopic studies have been conducted. H 3 + has been studied very extensively both experimentally and computationally in the last four decades, as was recently summarized in a very nice review. Despite its simplicity, the near-dissociation spectrum of H 3 + -recorded 40 years ago!-still remains unassigned. Partially due to its simplicity, H 3 + serves as a benchmark system for several different areas of science, in particular, high-resolution ro-vibrational spectroscopy experiments, accurate ab initio electronic structure calculations and potential energy surface (PES) development, high performance quantum dynamics calculations, and reaction dynamics. H 3 + can be found in the interstellar medium, supernova remnants, the atmospheres of gas giants, and exoplanets, and also plays an important role in star formation. It is the most common molecular ion in the Universe, serving as the main conduit of chemical reactions in outer space. The H 3 + molecular ion -the smallest tri-atomic molecular system, with just three protons and two electrons-is a central molecule in molecular astrophysics and astrochemistry. Such line lists are of huge importance in various astrochemical and astrophysical contexts. The main underlying motivation of our work is to provide a list of reliably labeled, spectroscopically accurate energy levels in a format that can be used in spectroscopic line lists, which are based on both experimental and theoretical levels. In addition, we performed an ab initio assignment of the ro-vibrational energy levels, providing vibrational ‘ v 1, v 2, | l|’ and rotational ‘ J, G, U, K’ quantum labels for more than 2,200 ro-vibrational states, including every single 0 ≤ J ≤ 20 state up to and above the barrier to linearity at 10,000 cm −1. In this work, we further improved the convergence accuracy and range of our ScalIT calculations for all J values up to J = 20 to a few 10 –5 cm −1 (or better). In a recent article, we carried out exact quantum dynamical calculations and computed ro-vibrational energy levels and wave functions for the H 3 + molecular ion up to the dissociation threshold (at J = 46) using a recently developed potential energy surface (PES) -arguably, the most accurate to date -together with the ScalIT suite of parallel codes.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |