MARVEL: measured active rotational-vibrational energy levels

An algorithm is proposed, based principally on an earlier proposition of Flaud and co-workers [Mol. Phys. 32 (1976) 499], that inverts the information contained in uniquely assigned experimental rotational-vibrational transitions in order to obtain measured active rotational-vibrational energy levels (MARVEL). The procedure starts with collecting, critically evaluating, selecting, and compiling all available measured transitions, including assignments and uncertainties, into a single database. Then, spectroscopic networks (SN) are determined which contain all interconnecting rotational-vibrational energy levels supported by the grand database of the selected transitions. Adjustment of the uncertainties of the lines is performed next, with the help of a robust weighting strategy, until a self-consistent set of lines and uncertainties is achieved. Inversion of the transitions through a weighted least-squares-type procedure results in MARVEL energy levels and associated uncertainties. Local sensitivity coefficients could be computed for each energy level. The resulting set of MARVEL levels is called active as when new experimental measurements become available the same evaluation, adjustment, and inversion procedure should be repeated in order to obtain more dependable energy levels and uncertainties. MARVEL is tested on the example of the H-2 O-17 isotopologue of water and a list of 2736 dependable energy levels, based on 8369 transitions, has been obtained. (c) 2007 Elsevier Inc. All rights reserved

Experimental energy levels and partition function of the 12^{12}C2_2 molecule

The carbon dimer, the $^{12}$C$_2$ molecule, is ubiquitous in astronomical environments. Experimental-quality rovibronic energy levels are reported for $^{12}$C$_2$, based on rovibronic transitions measured for and among its singlet, triplet, and quintet electronic states, reported in 42 publications. The determination utilizes the Measured Active Rotational-Vibrational Energy Levels (MARVEL) technique. The 23,343 transitions measured experimentally and validated within this study determine 5,699 rovibronic energy levels, 1,325, 4,309, and 65 levels for the singlet, triplet, and quintet states investigated, respectively. The MARVEL analysis provides rovibronic energies for six singlet, six triplet, and two quintet electronic states. For example, the lowest measurable energy level of the \astate\ state, corresponding to the $J=2$ total angular momentum quantum number and the $F_1$ spin-multiplet component, is 603.817(5) \cm. This well-determined energy difference should facilitate observations of singlet--triplet intercombination lines which are thought to occur in the interstellar medium and comets. The large number of highly accurate and clearly labeled transitions that can be derived by combining MARVEL energy levels with computed temperature-dependent intensities should help a number of astrophysical observations as well as corresponding laboratory measurements. The experimental rovibronic energy levels, augmented, where needed, with {\it ab initio} variational ones based on empirically adjusted and spin-orbit coupled potential energy curves obtained using the \Duo\ code, are used to obtain a highly accurate partition function, and related thermodynamic data, for $^{12}$C$_2$ up to 4,000 K.Comment: ApJ Supplements (in press), 48 page

Teljes rezgési-forgási színképek meghatározása = Determination of complete rotational-vibrational spectra

38 angol nyelvű és egy magyar nyelvű közlemény jelent meg, egy-egy a Nature (2008), a Chem. Eur. J. (2010) és a Phys. Rev. Lett. (2012) nagy hatástényezőjű folyóiratokban. A közlemények összesített impakt faktora több mint 100, a közleményekre már eddig több mint 250 hivatkozás érkezett. Komoly előrelépést értünk el a módszerfejlesztésekben, különös tekintettel a magmozgásoknak a kvantumkémia eszköztárával történő számítására. Ki- illetve továbbfejlesztettük a DOPI (discrete variable representation–orthogonal coordinates–product basis–iterative diagonalization), a DEWE (discrete variable representation–Eckart-Watson Hamiltonian–exact potential), a GENIUSH (general nuclear motion code with numerical, internal coordinate, user specified Hamiltonian), a MARVEL (measured active rotational-vibrational energy levels) és a NEAT (network of reaction enthalpis leading to atom-based thermochmistry) programrendszereket, bevezettük a spektroszkópiai hálózatok fogalmát, a rezgési-forgási hullámfüggvények értelmezésére kidolgoztuk a NMD (normal-mode decomposition) és RRD (rigid-rotor decomposition) eljárásokat. A kifejlesztett algoritmusokat és programrendszereket alkalmaztuk a spektroszkópiában és a termokémiában, különösen fontos szerkezeti és dinamikai eredményeket értünk el a H3+, H2O, NH3, CH4 és H2CCO molekulák és izotopológjaik kapcsán. Új eljárást dolgoztunk ki, mely a kísérleti, kvantumkémiai és információtechnológiai ismeretek kombinálásával segíti a molekulaspektroszkópiát. | 38 English and one Hungarian articles were published, one each in the high impact factor journals Nature (2008), Chem. Eur. J. (2010), and Phys. Rev. Lett. (2012). The cumulative impact of the publications is more than 100 and these articles have received more than 250 citations. Significant progress was made in our method development efforts, with emphasis on quantum chemical nuclear motion computations. We further developed our program systems allowing nuclear motion computations, including DOPI (discrete variable representation–orthogonal coordinates – product basis – iterative diagonalization), DEWE (discrete variable representation–Eckart-Watson Hamiltonian–exact potential), GENIUSH (general nuclear motion code with numerical, internal coordinate, user specified Hamiltonian), MARVEL (measured active rotational-vibrational energy levels), and NEAT (network of reaction enthalpies leading to atom-based thermochmistry), introduced the notion of spectroscopic networks, and to understand rovibrational wavefunctions we developed the normal-mode decomposition (NMD) and rigid-rotor decomposition (RRD) protocols. The algorithms and program systems developed were employed in computational molecular spectroscopy and thermochemistry, important structural and dynamical results were generated for H3+, H2O, NH3, CH4, H2CCO, and their isotopologues. A new approach combining experiment, quantum theory, and information technology, to high-resolution molecular spectroscopy was developed

Kis molekulák adatbázis alapú teljes spektroszkópiája = Database approach to the complete spectroscopy of small molecules

A Jonathan Tennyson professzorral (UCL, London, UK) csoportjával kezdeményezett kutatási együttműködés a számítógépes nagyfelbontású molekulaspektroszkópia területén valósult meg. A közös kutatómunka négy publikációt eredményezett, mindegyik a víz spektroszkópiájára vonatkozott, mely a legfontosabb földi üvegház hatású gáz. Az együttműködés keretében minden eddiginél pontosabb ab initio szemiglobális potenciális energia (PES) és dipólusmomentum (DMS) felületeket készítettünk a víz molekula elektron alapállapotára. Az azóta már többek által felhasznált PES neve CVRQD, míg a DMS-é CVR, ahol CV a törzs- és vegyértékelektronok korrelált mozgásának számítására utal, míg R a relativisztikus korrekcióra. A PES számítása során kvantumelektrodinamikai (QED) és diagonális Born-Oppenheimer korrekciók (DBOC) számítására is sor került. Egy további közleményben egy minden eddiginél pontosabb PES-t közöltünk a H2(16)O, H2(17)O és H2(18)O izotopológokra, mely a kísérleti adatokhoz történt illesztésen alapult. A MARVEL (Measured Active Rotational-Vibrational Energy Levels) algoritmus elkészítésében is közreműködött Tennyson professzor. | The research collaboration proposed with the group of Professor Jonathan Tennyson (UCL, London, UK) concerned the area of computational high-resolution molecular spectroscopy. The joint research resulted in four publications, all related to the spectroscopy of the water molecule, the most important greenhouse gas on Earth. Within the collaboration we developed ab initio semiglobal potential energy (PES) and dipole moment (DMS) surfaces of unprecedented accuracy for the ground electronic state of the water molecule. These PES and DMS surfaces, which have been used by many others since their development, are called CVRQD and CVR, respectively, where CV refers to the correlated motion electronic structure computations involving core and valence electrons, while R stand for the inclusion of relativistic effects. During the computation of the PES we considered quantum electrodynamic (QED) and diagonal Born-Oppenheimer (DBOC) effects, as well. In another publication we presented theup to now most accurate empirical PES for the isotopologues H2(16)O, H2(17)O, and H2(18)O, whose development was based on a refinement to existing observed data. Development of the MARVEL (Measured Active Rotational-Vibrational Energy Levels) procedure was also performed in collaboration with Professor Tennyson

On equilibrium structures of the water molecule

Equilibrium structures are fundamental entities in molecular sciences. They can be inferred from experimental data by complicated inverse procedures which often rely on several assumptions, including the Born-Oppenheimer approximation. Theory provides a direct route to equilibrium geometries. A recent high-quality ab initio semiglobal adiabatic potential-energy surface (PES) of the electronic ground state of water, reported by Polyansky [ ibid. 299, 539 (2003)] and called CVRQD here, is analyzed in this respect. The equilibrium geometries resulting from this direct route are deemed to be of higher accuracy than those that can be determined by analyzing experimental data. Detailed investigation of the effect of the breakdown of the Born-Oppenheimer approximation suggests that the concept of an isotope-independent equilibrium structure holds to about 3x10(-5) A and 0.02 degrees for water. The mass-independent [Born-Oppenheimer (BO)] equilibrium bond length and bond angle on the ground electronic state PES of water is r(e)(BO)=0.957 82 A and theta(e)(BO)=104.48(5)degrees, respectively. The related mass-dependent (adiabatic) equilibrium bond length and bond angle of (H2O)-O-16 is r(e)(ad)=0.957 85 A and theta(e)(ad)=104.50(0)degrees, respectively, while those of (D2O)-O-16 are r(e)(ad)=0.957 83 A and theta(e)(ad)=104.49(0)degrees. Pure ab initio prediction of J=1 and 2 rotational levels on the vibrational ground state by the CVRQD PESs is accurate to better than 0.002 cm(-1) for all isotopologs of water considered. Elaborate adjustment of the CVRQD PESs to reproduce all observed rovibrational transitions to better than 0.05 cm(-1) (or the lower ones to better than 0.0035 cm(-1)) does not result in noticeable changes in the adiabatic equilibrium structure parameters. The expectation values of the ground vibrational state rotational constants of the water isotopologs, computed in the Eckart frame using the CVRQD PESs and atomic masses, deviate from the experimentally measured ones only marginally, especially for A(0) and B-0. The small residual deviations in the effective rotational constants are due to centrifugal distortion, electronic, and non-Born-Oppenheimer effects. The spectroscopic (nonadiabatic) equilibrium structural parameters of (H2O)-O-16, obtained from experimentally determined A(0)(') and B-0(') rotational constants corrected empirically to obtain equilibrium rotational constants, are r(e)(sp)=0.957 77 A and theta(e)(sp)=104.48 degrees

MARVEL analysis of the measured high-resolution rovibrational spectra of C2H2

Rotation-vibration energy levels are determined for the electronic ground state of the acetylene molecule, $^{12}$C$_2$H$_2$, using the Measured Active Rotational-Vibrational Energy Levels (MARVEL) technique. 37,813 measured transitions from 61 publications are considered. The distinct components of the spectroscopic network linking ortho and para states are considered separately. The 20,717 ortho and 17,096 para transitions measured experimentally are used to determine 6013 ortho and 5200 para energy levels. The MARVEL results are compared with alternative compilations based on the use of effective Hamiltonians.Comment: 55 pages, 8 figures, JQSRT, 201

MARVEL Analysis of the Measured High-Resolution Rovibronic Spectra of 90Zr16O

Zirconium oxide(ZrO) is an important astrophysical molecule that defines the S-star classification class for cool giant stars. Accurate, empirical rovibronic energy levels, with associated labels and uncertainties, are reported for 9 low-lying electronic states of the diatomic 90Zr16O molecule. These 8088 empirical energy levels are determined using the Marvel (Measured Active Rotational-Vibrational Energy Levels) algorithm with 23 317 input assigned transition frequencies, 22 549 of which were validated. A temperature-dependent partition function is presented alongside updated spectroscopic constants for the 9 low-lying electronic states

Recommended ideal-gas thermochemical functions for heavy water and its Substituent isotopologues

Accurate temperature-dependent ideal-gas internal partition functions, Qint(T), and several derived thermochemical functions are reported for heavy water, with an oxygen content corresponding to the isotopic composition of Vienna Standard Mean Ocean Water (VSMOW), and its constituent isotopologues, D216O, D217O, and D218O, for temperatures between 0 and 6000 K. The nuclear-spin-dependent partition functions are obtained by the direct summation technique, involving altogether about 16 000 measured and more than nine million computed bound rovibrational energy levels for the three molecules. Reliable standard uncertainties, as a function of temperature, are estimated for each thermochemical quantity determined, including the enthalpy, the entropy, and the isobaric heat capacity of the individual nuclear-spin-equilibrated isotopologues and of heavy water. The accuracy of the heavy-water ideal-gas Cp(T) is unprecedented, below 0.01% up to 1800 K. All the thermochemical functions are reported, in 1 K increments, in the supplementary material