Simulating the HeI photoelectron spectrum of ClO with new full-dimensional adiabatic potential energy surfaces of ClO(X̃A), ClO(X̃B), and ClO(C̃A) and a three-state diabatic potential energy matrix of ClO(ÃB, B̃A, and 2A): a quantum mechanical study.

To interpret the HeI photoelectron spectrum of ClO (involving four lowest electronic states of ClO), in this work we first constructed the associated adiabatic full-dimensional potential energy surfaces (PESs) of ClO(X̃A), ClO(X̃B), and ClO(C̃A) and a diabatic potential energy matrix (PEM) of ClO(AB, B̃A, and 2A) using the explicitly correlated internally contracted multi-reference configurational interaction with Davidson correction (MRCI-F12+Q) and neural network methods. Particularly for the AB, B̃A, and 2A states of ClO coupled in terms of conical intersection, their diabatization is achieved by the neural network approach based merely on the associated adiabatic energies. With the help of newly constructed adiabatic PESs and the diabatic PEM, the HeI photoelectron spectrum of ClO is further computed quantum mechanically.

Association Between Hepatocellular Carcinoma and Type 2 Diabetes Mellitus in Chinese Hepatitis B Virus Cirrhosis Patients: A Case-Control Study.

BACKGROUND Whether the presence of type 2 diabetes mellitus (T2DM) increases the risk of hepatocellular carcinoma (HCC) in hepatitis B virus (HBV) cirrhosis patients is controversial. We conducted a retrospective case-control study to evaluate this issue. MATERIAL AND METHODS We considered all patients diagnosed with HBV-related liver cirrhosis at our hospital from July 2011 to June 2014.

Calculations of the active mode and energetic barrier to electron attachment to CF and comparison with kinetic modeling of experimental results.

To provide a deeper understanding of the kinetics of electron attachment to CF, the six-dimensional potential energy surfaces of both CF and CF were developed by fitting ∼3000 ab initio points per surface at the AE-CCSD(T)-F12a/AVTZ level using the permutation invariant polynomial-neural network (PIP-NN) approach. The fitted potential energy surfaces for CF and CF had root mean square fitting errors relative to the ab initio calculations of 1.2 and 1.

Full-Dimensional Quantum Calculations of Vibrational Levels of NH4(+) and Isotopomers on An Accurate Ab Initio Potential Energy Surface.

Vibrational energy levels of the ammonium cation (NH4(+)) and its deuterated isotopomers are calculated using a numerically exact kinetic energy operator on a recently developed nine-dimensional permutation invariant semiglobal potential energy surface fitted to a large number of high-level ab initio points. Like CH4, the vibrational levels of NH4(+) and ND4(+) exhibit a polyad structure, characterized by a collective quantum number P = 2(v1 + v3) + v2 + v4. The low-lying vibrational levels of all isotopomers are assigned and the agreement with available experimental data is better than 1 cm(-1).

Quantum Dynamics of Vinylidene Photodetachment on an Accurate Global Acetylene-Vinylidene Potential Energy Surface.

Vinylidene is a high-energy isomer of acetylene, and the rearrangement of bonds in the two species serves as a prototype for isomerization reactions. Here, a full-dimensional quantum mechanical study of the vinylidene vibration is carried out on a recently developed global acetylene-vinylidene potential energy surface by simulating the photodetachment dynamics of the vinylidene anion. Several low-lying vibrational levels of the anion were first determined on a new ab initio based potential energy surface, and their photoelectron spectra were obtained within the Condon approximation.

Near spectroscopically accurate ab initio potential energy surface for NH4(+) and variational calculations of low-lying vibrational levels.

A nine-dimensional potential energy surface (PES) for the ammonium cation has been constructed by fitting ∼30 000 AE-CCSD(T)-F12a/cc-pCVTZ-F12 points up to 32 262 cm(-1) (4.0 eV) from the minimum. The fitting using the permutation invariant polynomial-neural network method has high fidelity, with a root-mean-square error of merely 2.

Relativistic configuration interaction calculation on the ground and excited states of iridium monoxide.

We present the fully relativistic multi-reference configuration interaction calculations of the ground and low-lying excited electronic states of IrO for individual spin-orbit component. The lowest-lying state is calculated for Ω = 1/2, 3/2, 5/2, and 7/2 in order to clarify the ground state of IrO. Our calculation suggests that the ground state is of Ω = 1/2, which is highly mixed with (4)Σ(-) and (2)Π states in Λ - S notation.

Toward spectroscopically accurate global ab initio potential energy surface for the acetylene-vinylidene isomerization.

A new full-dimensional global potential energy surface (PES) for the acetylene-vinylidene isomerization on the ground (S0) electronic state has been constructed by fitting ∼37,000 high-level ab initio points using the permutation invariant polynomial-neural network method with a root mean square error of 9.54 cm(-1). The geometries and harmonic vibrational frequencies of acetylene, vinylidene, and all other stationary points (two distinct transition states and one secondary minimum in between) have been determined on this PES.

New schemes for internally contracted multi-reference configuration interaction.

In this work we present a new internally contracted multi-reference configuration interaction (MRCI) scheme by applying the graphical unitary group approach and the hole-particle symmetry. The latter allows a Distinct Row Table (DRT) to split into a number of sub-DRTs in the active space. In the new scheme a contraction is defined as a linear combination of arcs within a sub-DRT, and connected to the head and tail of the DRT through up-steps and down-steps to generate internally contracted configuration functions.

New implementation of the configuration-based multi-reference second order perturbation theory.

We present an improved version of the configuration-based multi-reference second-order perturbation approach (CB-MRPT2) according to the formulation of Lindgren on perturbation theory of a degenerate model space. This version involves a reclassification of the perturbation functions and new algorithms to calculate matrix elements in the perturber energy expressions utilizing the graphical unitary group approach and the hole-particle symmetry. The diagonalize-then-perturb (DP), including Rayleigh-Schrödinger and Brillouin-Wigner, and diagonalize-then-perturb-then-diagonalize (DPD) modes have been implemented.

Global ab initio potential energy surfaces for both the ground (X̃1A') and excited (Ã1A'') electronic states of HNO and vibrational states of the Renner-Teller Ã1A''-X̃1A' system.

The global potential energy surfaces for both the ground (X̃(1)A(')) and excited (Ã(1)A('')) electronic states of the HNO molecule have been constructed by three-dimensional cubic spline interpolation of more than 17,000 ab initio points, which have been calculated at the internal contracted multi-reference configuration interaction level with the Davidson correction using an augmented correlation-consistent polarized valence quadruple zeta basis set. The low-lying vibrational energy levels for the two electronic states of HNO have also been calculated on our potential energy surfaces including the diagonal Renner-Teller terms. The calculated results have shown a good agreement with the experimental vibrational frequencies of HNO and its isotopomers.

Electronic structure calculations of low-lying electronic states of O3.

Configuration-based multi-reference second order perturbation theory (CB-MRPT2) and multi-reference configuration interaction with single and double excitations (MRCISD) have been used to calculate the bending and dissociation potential energy curves (PECs) of ozone. Based on these PECs, equilibrium structures, vertical and adiabatic transition energies of the ground state and several low-lying excited states, as well as intersections and avoided crossings among the states displayed on the PECs are investigated. The energy separation of the open and ring structures and the dissociation energy of the ground state X(1)A(1) are determined by reference-selected MRCISD.

Potential energy curves and interpretation of electronic spectrum of the rhodium monoxide.

Potential energy curves of 17 electronic states of rhodium monoxide (RhO) are calculated by multireference configuration interaction with single and double excitations (MRCISD). The ground state of RhO is determined to be a (4)Sigma(-) state with equilibrium bond length of 1.710 A and harmonic vibrational frequency of 825 cm(-1) at the MRCISD level of theory.

The potential energy curves of low-lying electronic states of S2O.

Potential energy curves (PECs) of the symmetric and asymmetric bent S(2)O molecules are constructed using the configuration-based multireference second order perturbation theory and multireference configuration interaction with single and double excitations. Based on the PECs, the equilibrium structures of the ground state and several low-lying excited states, as well as the vertical and adiabatic transition energies, are obtained. Furthermore, avoided crossings and intersections displayed on the PECs are studied.