Huidong Li

Bio: Huidong Li is an academic researcher from Xihua University. The author has contributed to research in topics: Diatomic molecule & Rotational–vibrational spectroscopy. The author has an hindex of 8, co-authored 58 publications receiving 275 citations. Previous affiliations of Huidong Li include University of Georgia & Sichuan University.

The alkaline earth dimer cations (Be2 +, Mg2 +, Ca2 +, Sr2 +, and Ba2 +). Coupled cluster and full configuration interaction studies†

Abstract: Although all of the neutral alkaline earth dimers have been studied experimentally, only for the beryllium and strontium systems have the diatomic radical cations been subjected to modern spectroscopic techniques. In the present research, both coupled cluster and full configuration interaction methods were used to describe the M2 + systems. Basis sets as large as aug-cc-pCV5Z were chosen. For both Be2 + and Sr2 + agreement with the experiments is outstanding. Final predictions for the unknown dissociation energies are 10,651 (Mg2 +), 9605 (Ca2 +), and 8980 cm−1 (Ba2 +). The M2 + dissociation energies decrease monotonically going down the periodic except for the Sr2 + - Ba2 + pair. The unknown bond distances re are 3.015 (Mg2 +), 3.814 (Ca2 +), 4.194 (Sr2 +), and 4.587 A (Ba2 +).

Extreme metal carbonyl back bonding in cyclopentadienylthorium carbonyls generates bridging C2O2 ligands by carbonyl coupling.

Abstract: Laboratory studies of the interaction of carbon monoxide with organoactinides result in the formation of isolable complexes such as Cp3UCO derivatives (Cp = cyclopentadienyl) as well as coupling reactions to give derivatives of the oligomeric anions CnOn2– (n = 2, 3, 4). To gain some insight into actinide carbonyl chemistry, binuclear cyclopentadienylthorium carbonyls Cp2Th2(CO)n (n = 2 to 5) as model compounds have been investigated using density functional theory. The most favorable such structures in terms of energy and thermochemistry are the tricarbonyl Cp2Th2(η2-μ-CO)3 having three four-electron donor bridging carbonyl groups and the tetracarbonyl Cp2Th2(η4-μ-C2O2)(η2-μ-CO)2 having not only two four-electron donor bridging carbonyl groups but also a bridging ethynediolate ligand formed by coupling two CO groups through C–C bond formation. The bridging infrared ν(CO) frequencies ranging from 1140 to 1560 cm–1 in these Cp2Th2(CO)n (n = 3, 4) derivatives indicate extremely strong Th→CO back bonding in ...

A new type of sandwich compound: homoleptic bis(trimethylenemethane) complexes of the first row transition metals

Abstract: The metal carbonyl complexes [η4-(CH2)3C]Fe(CO)3 and [η4-(CH2)3C]Cr(CO)4 have been synthesized containing the umbrella-shaped trimethylenemethane ligand. The prospect of using this ligand in the metal sandwich complexes [(CH2)3C]2M (M = Ti, V, Cr, Mn, Fe, Co, Ni) has now been investigated by density functional theory. The lowest energy structures of such complexes have the metal atom sandwiched between two tetrahapto trimethylenemethane ligands. Singlet spin state structures are strongly preferred for the titanium and nickel derivatives and doublet spin state structures for the vanadium and cobalt derivatives. Similarly, the triplet spin state is preferred for the iron derivative by more than 11 kcal mol−1. The preferred spin states for the chromium and manganese derivatives depend on the functional used for the structure optimization. Thus the B3LYP and B3LYP* methods predict the higher spin states, namely triplet for chromium and quartet for manganese. However, the BP86 method predicts the lower spin states of singlet for chromium and doublet for manganese. The higher spin state structures for the late transition metal derivatives, namely quintet [(CH2)3C]2Fe, quartet [(CH2)3C]2Co, and triplet [(CH2)3C]2Ni, have trihapto rather than tetrahapto trimethylenemethane ligands. The frontier molecular orbitals in the singlet [(CH2)3C]2M derivatives (M = Ti, Ni) suggest strong metal–ligand σ and π bonding but insignificant metal–ligand δ bonding.

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Rotational Spectroscopy of Diatomic Molecules

Abstract: 1. General introduction 2. The separation of nuclear and electronic motion 3. The electronic hamiltonian 4. Interactions arising from nuclear magnetic and electric moments 5. Angular momentum theory and spherical tensor algebra 6. Electronic and vibrational states 7. Derivation of the effective hamiltonian 8. Molecular beam magnetic and electric resonance 9. Microwave and far-infrared magnetic resonance 10. Pure rotational spectroscopy 11. Double resonance spectroscopy Appendices.

Molecules in a Bose-Einstein condensate

Abstract: State-selected rubidium-87 molecules were created at rest in a dilute Bose-Einstein condensate of rubidium-87 atoms with coherent free-bound stimulated Raman transitions. The transition rate exhibited a resonance line shape with an extremely narrow width as small as 1.5 kilohertz. The precise shape and position of the resonance are sensitive to the mean-field interactions between the molecules and the atomic condensate. As a result, we were able to measure the molecule-condensate interactions. This method allows molecular binding energies to be determined with unprecedented accuracy and is of interest as a mechanism for the generation of a molecular Bose-Einstein condensate.

Automatic Generation of Auxiliary Basis Sets

Abstract: A procedure was developed to automatically generate auxiliary basis sets (ABSs) for use with the resolution of the identity (RI) approximation, starting from a given orbital basis set (OBS). The goal is to provide an accurate and universal solution for cases where no optimized ABSs are available. In this context, “universal” is understood as the ability of the ABS to be used for Coulomb, exchange, and correlation energy fitting. The generation scheme (denoted AutoAux) works by spanning the product space of the OBS using an even-tempered expansion for each atom in the system. The performance of AutoAux in conjunction with different OBSs [def2-SVP, def2-TZVP, def2-QZVPP, and cc-pwCVnZ (n = D, T, Q, 5)] has been evaluated for elements from H to Rn and compared to existing predefined ABSs. Due to the requirements of simplicity and universality, the generated ABSs are larger than the optimized ones but lead to similar errors in MP2 total energies (on the order of 10–5 to 10–4 Eh/atom).

BOUT++: A framework for parallel plasma fluid simulations

Abstract: Abstract A new modular code called BOUT++ is presented, which simulates 3D fluid equations in curvilinear coordinates. Although aimed at simulating Edge Localised Modes (ELMs) in tokamak x -point geometry, the code is able to simulate a wide range of fluid models (magnetised and unmagnetised) involving an arbitrary number of scalar and vector fields, in a wide range of geometries. Time evolution is fully implicit, and 3rd-order WENO schemes are implemented. Benchmarks are presented for linear and non-linear problems (the Orszag–Tang vortex) showing good agreement. Performance of the code is tested by scaling with problem size and processor number, showing efficient scaling to thousands of processors. Linear initial-value simulations of ELMs using reduced ideal MHD are presented, and the results compared to the ELITE linear MHD eigenvalue code. The resulting mode-structures and growth-rate are found to be in good agreement ( γ BOUT++ = 0.245 ω A , γ ELITE = 0.239 ω A , with Alfvenic timescale 1 / ω A = R / V A ). To our knowledge, this is the first time dissipationless, initial-value simulations of ELMs have been successfully demonstrated.