Do you want to publish a course? Click here

Modelling the Vibration-Rotation Energy Levels of D218O molecule with Effective Hamiltonian Method

49   0   0.0 ( 0 )
 Added by Olga Naumenko
 Publication date 2021
  fields Physics
and research's language is English




Ask ChatGPT about the research

Using the effective rotational Hamiltonian method, we have conducted an analysis of the D218O ground and the first excited vibration state rotational energy levels. The analysis was based on the effective Hamiltonians represented in several forms: the Watson Hamiltonian, the Hamiltonian expressed in terms of Pade-Borel approximants, and the Hamiltonian in terms of generating function expansions. The rotational and centrifugal constants have been determined from the fitting, which describe the rotational energy levels with an accuracy close to that of the experimental data. The predictive performance of the model with respect to highly excited rotational states has been evaluated against the global variation calculations. The radii of convergence of the effective rotation Hamiltonian series have been determined.



rate research

Read More

A variationally computed $^{28}$SiH$_4$ rotation-vibration line list applicable for temperatures up to $T=1200,$K is presented. The line list, called OY2T, considers transitions with rotational excitation up to $J=42$ in the wavenumber range $0$--$5000,$cm$^{-1}$ (wavelengths $lambda> 2,mu$m). Just under 62.7 billion transitions have been calculated between 6.1 million energy levels. Rovibrational calculations have utilized a new `spectroscopic potential energy surface determined by empirical refinement to 1452 experimentally derived energy levels up to $J=6$, and a previously reported textit{ab initio} dipole moment surface. The temperature-dependent partition function of silane, the OY2T line list format, and the temperature dependence of the OY2T line list are discussed. Comparisons with the PNNL spectral library and other experimental sources indicate that the OY2T line list is robust and able to accurately reproduce weaker intensity features. The full line list is available from the ExoMol database and the CDS database.
The frozen domain effective fragment molecular orbital method is extended to allow for the treatment of a single fragment at the MP2 level of theory. The approach is applied to the conversion of chorismate to prephenate by chorismate mutase, where the substrate is treated at the MP2 level of theory while the rest of the system is treated at the RHF level. MP2 geometry optimization is found to lower the barrier by up to 3.5 kcal/mol compared to RHF optimzations and ONIOM energy refinement and leads to a smoother convergence with respect to the basis set for the reaction profile. For double zeta basis sets the increase in CPU time relative to RHF is roughly a factor of two.
The cluster-in-molecule (CIM) local correlation approach with an accurate distant pair correlation energy correction is presented. For large systems, the inclusion of distant pair correlation energies is essential for the accurate predictions of absolute correlation energies and relative energies. Here we propose a simple and efficient scheme for evaluating the distant pair correlation energy correction. The corrections can be readily extracted from electron correlation calculations of clusters with almost no additional effort. Benchmark calculations show that the improved CIM approach can recover more than 99.97% of the conventional correlation energy. By combining the CIM approach with the domain based local pair natural orbital (DLPNO) local correlation approach, we have provided accurate binding energies at the CIM-DLPNO-CCSD(T) level for a test set consisting of eight weakly bound complexes ranging in size from 200 to 1027 atoms. With these results as the reference data, the accuracy and applicability of other electron correlation methods and a few density functional methods for large systems have been assessed.
99 - Y. Hatta , E. Iancu , L. McLerran 2005
We construct the effective Hamiltonian which governs the renormalization group flow of the gluon distribution with increasing energy and in the leading logarithmic approximation. This Hamiltonian defines a two-dimensional field theory which involves two types of Wilson lines: longitudinal Wilson lines which describe gluon recombination (or merging) and temporal Wilson lines which account for gluon bremsstrahlung (or splitting). The Hamiltonian is self-dual, i.e., it is invariant under the exchange of the two types of Wilson lines. In the high density regime where one can neglect gluon number fluctuations, the general Hamiltonian reduces to that for the JIMWLK evolution. In the dilute regime where gluon recombination becomes unimportant, it reduces to the dual partner of the JIMWLK Hamiltonian, which describes bremsstrahlung.
Potential energy surfaces of the hydrogen molecular ion H$_2^+$ in the Born-Oppenheimer approximation are computed by means of the Riccati-Pade method (RPM). The convergence properties of the method are analyzed for different states. The equilibrium internuclear distance, as well as the corresponding electronic plus nuclear energy, and the associated separation constants, are computed to 40 digits of accuracy for several bound states. For the ground state the same parameters are computed with more than 100 digits of accuracy. Additional benchmark values of the electronic energy at different internuclear distances are given for several additional states. The software implementation of the RPM is given under a free software license. The results obtained in the present work are the most accurate available so far, and further additional benchmarks are made available through the software provided.
comments
Fetching comments Fetching comments
Sign in to be able to follow your search criteria
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا