All-electron relativistic spin-orbit multireference computation to elucidate the ground state of CeH.

The all-electron relativistic spin-orbit multiconfiguration/multireference computations with the Sapporo basis sets were carried out to elucidate the characters of the low-lying quasi-degenerate electronic states for the CeH diatomic molecule. The present computations predict the ground state of CeH to be a pure quartet state of 4f15d1(5dσ-H1s)26s1 configuration (Ω = 3.5). The first excited state (Ω = 2.5) shows a doublet dominant of 4f1(5dσ-H1s)26s2 configuration at a short bond length while it changes to a quartet dominant at a long bond length. The Ce-H stretching fundamental frequency was calculated to be 1345 cm-1 in the ground state, which is in good agreement with the experimental value, 1271 cm-1, measured by a matrix-isolation technique.

All-electron relativistic computations on the low-lying electronic states, bond length, and vibrational frequency of CeF diatomic molecule with spin-orbit coupling effects.

Ab initio all-electron computations have been carried out for Ce+ and CeF, including the electron correlation, scalar relativistic, and spin-orbit coupling effects in a quantitative manner. First, the n-electron valence state second-order multireference perturbation theory (NEVPT2) and spin-orbit configuration interaction (SOCI) based on the state-averaged restricted active space multiconfigurational self-consistent field (SA-RASSCF) and state-averaged complete active space multiconfigurational self-consistent field (SA-CASSCF) wavefunctions have been applied to evaluations of the low-lying energy levels of Ce+ with [Xe]4f1 5d1 6s1 and [Xe]4f1 5d2 configurations, to test the accuracy of several all-electron relativistic basis sets. It is shown that the mixing of quartet and doublet states is essential to reproduce the excitation energies. Then, SA-RASSCF(CASSCF)/NEVPT2 + SOCI computations with the Sapporo(-DKH3)-2012-QZP basis set were carried out to determine the energy levels of the low-lying electronic states of CeF. The calculated excitation energies, bond length, and vibrational frequency are shown to be in good agreement with the available experimental data. © 2018 Wiley Periodicals, Inc.

Pharmacodynamics of vancomycin in elderly patients aged 75 years or older with methicillin-resistant Staphylococcus aureus hospital-acquired pneumonia.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) infections are associated with significant mortality and health care costs. To improve treatment outcomes for MRSA, a better understanding of the pharmacokinetic/pharmacodynamic parameters of vancomycin is required to develop optimal dosing strategies, particularly in elderly patients (≥75 years of age) with limited renal function. The purpose of this study was to determine whether pharmacokinetic indices for vancomycin are associated with mortality from MRSA hospital-acquired pneumonia in elderly patients. METHODS: We conducted a retrospective observational study with 28-day mortality as the primary outcome for 94 patients with MRSA hospital-acquired pneumonia who had been treated with vancomycin from January 2006 through December 2012. Our most recent sampling of MRSA isolates had a minimum inhibitory concentration (MIC) for vancomycin of 1 µg/mL (86%), indicating that the area under the curve (AUC) was equal to the AUC/MIC in these isolates. The primary data from 28-day survivors and nonsurvivors were compared. RESULTS: Among 94 elderly patients, the mean age was 82 (75-99) years. Multivariate analyses revealed that, among the factors examined, only the nonoptimal AUC (<250, >450 µg*h/mL) was an independent predictor of 28-day mortality in elderly patients (odds ratio 23.156, 95% confidence interval 6.814-78.687, P < 0.001). We detected a significant difference for increasing nephrotoxicity in nonsurvivors (nine of 32 patients [28%]) compared with survivors (three of 62 patients [4.8%], P = 0.003). CONCLUSION: This finding indicates that patients with potentially poor renal function are likely to have increased AUC values and a poor prognosis. Consideration of the pharmacokinetics/pharmacodynamics of vancomycin and targeting an AUC/MIC value of 250-450 µg*h/mL may result in improved treatment outcomes for elderly patients with MRSA hospital-acquired pneumonia.

A multireference perturbation study of the NN stretching frequency of trans-azobenzene in nπ* excitation and an implication for the photoisomerization mechanism.

A multireference second-order perturbation theory is applied to calculate equilibrium structures and vibrational frequencies of trans-azobenzene in the ground and nπ* excited states, as well as the reaction pathways for rotation and inversion mechanism in the nπ* excited state. It is found that the NN stretching frequency exhibits a slight increase at the minimum energy structure in the nπ* state, which is explained by the mixing of the NN stretching mode with the CN symmetric stretching mode. We also calculate the NN stretching frequency at several selected structures along the rotation and inversion pathways in the nπ* state, and show that the frequency decreases gradually along the rotation pathway while it increases by ca. 300 cm(-1) along the inversion pathway. The frequencies and energy variations along the respective pathways indicate that the rotation pathway is more consistent with the experimental observation of the NN stretching frequency in nπ* excitation.

Polypharmacy with common diseases in hospitalized elderly patients.

BACKGROUND: Elderly persons are exposed to polypharmacy because of multiple chronic conditions. Many risk factors for polypharmacy have been identified including age, race/ethnicity, sex, educational achievement level, health status, and number of chronic diseases. However, drugs prescribed for individual diseases have not been analyzed. OBJECTIVE: The objective of this study was to analyze each common disease in the elderly with respect to prescribed drugs and polypharmacy. METHODS: A 1-year (January through December 2009) cross-sectional study was performed in which all drugs given to hospitalized elderly patients (age, >65 years) were investigated. Common diseases of the elderly were separated into disease groups including hypertension, hyperlipidemia, gastric ulcer, previous stroke, reflux esophagitis, diabetes mellitus, malignancy, osteoporosis, angina pectoris, congestive heart failure, chronic obstructive pulmonary disease, dementia, and depression. RESULTS: Among 1768 elderly patients, the mean (range) age of study patients was 78 (65 to 100) years. The mean (SD) number of diseases was 7.7 (3.4), and the number of drugs overall was 4.9 (3.6). The number of drugs and prevalence of polypharmacy were hypertension, 5.2 (3.9 [51%]); hyperlipidemia, 5.6 (3.8 [58%]); gastric ulcer, 5.4 (3.8 [53%]); previous stroke, 5.8 (3.2 [61%]); reflux esophagitis, 5.6 (3.8 [40%]), diabetes mellitus, 5.6 (3.1 [54%]); malignancy, 4.1 (3.1 [37%]); osteoporosis, 5.4 (3.4 [45%]); angina pectoris, 5.7 (3.6 [42%]); congestive heart failure, 6.1 (4.0 [60%]); chronic obstructive pulmonary disease, 5.0 (3.5 [53%]); dementia, 5.1 (3.2 [52%]); and depression, 7.0 (4.2 [73%]). CONCLUSIONS: When assessing the risk of polypharmacy, physicians should carefully consider the type of any chronic disease. Elderly patients with multiple diseases may be subjected to further polypharmacy.

Relativistic correlating basis sets for 57La and 89Ac.

Developed and reported are compact yet efficient correlating basis sets for the (57)La and (89)Ac atoms, missing in the literature. Good performance of these correlating sets is exemplified in molecular applications to diatomic oxides and fluorides.

Ab initio molecular dynamics simulation of photoisomerization in azobenzene in the n pi* state.

Photoisomerization mechanism of azobenzene in the lowest excited state S(1)(n pi(*)) is investigated by ab initio molecular dynamics (AIMD) simulation with the RATTLE algorithm, based on the state-averaged complete active space self-consistent field method. AIMD simulations show that cis to trans isomerization occurs via two-step rotation mechanism, accompanying rotations of the central NN part and two phenyl rings, and this process can be classified into two types, namely, clockwise and counterclockwise rotation pathways. On the other hand, trans to cis isomerization occurs via conventional rotation pathway where two phenyl rings rotate around the NN bond. The quantum yields are calculated to be 0.45 and 0.28+/-0.14 for cis to trans and trans to cis photoisomerizations, respectively, which are in very good agreement with the corresponding experimental results.

Ab initio QM/MM molecular dynamics study on the excited-state hydrogen transfer of 7-azaindole in water solution.

Ab initio molecular dynamics (AIMD) simulations for the excited-state hydrogen transfer (ESHT) reaction of 7-azaindole (7AI-(H2O)n; n = 1, 2) clusters in the gas phase and in water are presented. The effective fragment potential (EFP) is employed to model the surrounding water molecules. The AIMD simulations for 7AI-H2O and 7AI-(H2O)2 clusters show an asynchronous hydrogen transfer at t approximately 50 fs after the photoexcitation. While the ESHT mechanism for 7AI-H2O in water does not change appreciably compared with that in the gas phase, the AIMD simulations on 7AI-(H2O)2 in water solution exhibit two different mechanisms. Since the tautomer form is lower in energy compared to the normal form in the S1 state, 7AI and (H2O) n fragments separate from each other after the ESHT. With the use of the results of the AIMD trajectories, the minimum energy conical intersection point in the tautomer region has also been located.

Identification of the matrix shift: a fingerprint for neutral neon complex?

Ar-NiCO and Ne-NiCO have been predicted as novel neutral noble gas charge-transfer complexes, with binding energies of 7.70 and 2.16 kcal/mol, respectively, by the highly correlated coupled-cluster singles and doubles including a perturbational estimate of triple excitations calculations. The calculated shifts in the Ni-C-O bending frequency are 48 and 36 cm(-1) for Ar-NiCO and Ne-NiCO, while the corresponding experimental matrix shifts are 46 and 36 cm(-1), respectively. The anharmonicity effects for these frequencies are verified to be very small. The interaction between a noble gas atom and NiCO is discussed through natural population analyses and the electron density difference map. We further examined the noble gas matrix effects on the geometrical structure and vibrational frequencies of NiCO by performing density functional theory calculations for the Ng31-NiCO (Ng = Ar, Ne, He) system. The present results will inspire the further experimental investigation on the complexes of noble gas and transition metal compounds generated in the matrix isolation experiments.

Relativistic correlating basis sets for actinide atoms from 90Th to 103Lr.

For 14 actinide atoms from (90)Th to (103)Lr, contracted Gaussian-type function sets are developed for the description of correlations of the 5f, 6d, and 7s electrons. Basis sets for the 6d orbitals are also prepared, since the orbitals are important in molecular environments despite their vacancy in the ground state of some actinides. A segmented contraction scheme is employed for the compactness and efficiency. Contraction coefficients and exponents are so determined as to minimize the deviation from accurate natural orbitals of the lowest term arising from the 5f(n-1)6d(1)7s(2) configuration. The spin-free relativistic effects are considered through the third-order Douglas-Kroll approximation. To test the present correlating sets, all-electron calculations are performed on the ground state of (90)ThO molecule. The calculated spectroscopic constants are in excellent agreement with experimental values.

Theoretical prediction of noble-gas compounds: Ng-Pd-Ng and Ng-Pt-Ng.

Following our recent study on Ng-Pt-Ng (Ng=Ar,Kr,Xe) [J. Chem. Phys. 123, 204321 (2005)], the binding of noble-gas atoms with Pd atom has been investigated by the ab initio coupled cluster CCSD(T) method with counterpoise corrections, including relativistic effects. It is shown that two Ng atoms bind with Pd atom in linear geometry due to the s-d(sigma) hybridization in Pd where the second Ng atom attaches with much larger binding energy than the first. The binding energies are evaluated as 4.0, 10.2, and 21.5 kcalmol for Ar-Pd-Ar, Kr-Pd-Kr, and Xe-Pd-Xe, respectively, relative to the dissociation limit, Pd ((1)S)+2Ng. In the hybrid Ng complexes, the binding energies for XePd and Ng (=Ar,Kr) are evaluated as 4.0 and 6.9 kcalmol for XePd-Ar and XePd-Kr, respectively. The fundamental frequencies and low-lying vibrational-rotational energy levels are determined for each compound by the variational method, based on the three-dimensional near-equilibrium potential energy surface. Results of vibrational-rotational analyses for Ng-Pt-Ng (Ng=Ar,Kr,Xe) and Xe-Pt-Ng (Ng=He,Ne,Ar,Kr) compounds are also given.

Relativistic correlating basis sets for lanthanide atoms from Ce to Lu.

Contracted Gaussian-type function (CGTF) sets for the description of the 4f subshell correlation and of the 6s and 5d subshell correlation are developed for lanthanide atoms from Ce to Yb. Also prepared are basis sets for the 5d orbitals, which are vacant in the ground states of most lanthanide atoms but are essential in molecular environments. In addition, correlating CGTF sets for the 4f subshell correlation are supplemented for the Lu atom. A segmented contraction scheme is employed for their compactness and efficiency. Contraction coefficients and exponents are determined by minimizing the deviation from accurate natural orbitals generated from configuration interaction calculations that include relativistic effects through the third-order Douglas-Kroll approximation. All-electron and model core potential calculations with the present correlating sets are performed on the ground state of the diatomic CeO molecule. The calculated spectroscopic constants are in good agreement with experimental values.

Theoretical study of Pt-Ng and Ng-Pt-Ng (Ng=Ar,Kr,Xe).

We have investigated the binding of noble-gas (Ng) atoms (Ng=Ar,Kr,Xe) with Pt atom by the ab initio coupled-cluster CCSD(T) method, taking into account the relativistic effects. It is shown that two Ng atoms can bind with Pt atom in linear geometry in the singlet lowest state where the second Ng atom attaches to Pt with the larger binding energy than the first Ng atom. The binding energy is evaluated as 8.2, 17.9, and 33.4 kcal/mol for Ar-Pt-Ar, Kr-Pt-Kr, and Xe-Pt-Xe, respectively, relative to the triplet ground state of the dissociation limit Pt ((3)D)+2Ng. The present results indicate that these Ng-Pt-Ng compounds are possible new gas-phase or matrix species.

Compact and efficient basis sets of s- and p-block elements for model core potential method.

We propose compact and efficient valence-function sets for s- and p-block elements from Li to Rn to appropriately describe valence correlation in model core potential (MCP) calculations. The basis sets are generated by a combination of split MCP valence orbitals and correlating contracted Gaussian-type functions in a segmented form. We provide three types of basis sets. They are referred to as MCP-dzp, MCP-tzp, and MCP-qzp, since they have the quality comparable with all-electron correlation consistent basis sets, cc-pVDZ, cc-pVTZ, and cc-pVQZ, respectively, for lighter atoms. MCP calculations with the present basis sets give atomic correlation energies in good agreement with all-electron calculations. The present MCP basis sets systematically improve physical properties in atomic and molecular systems in a series of MCP-dzp, MCP-tzp, and MCP-qzp. Ionization potentials and electron affinities of halogen atoms as well as molecular spectroscopic constants calculated by the best MCP set are in good agreement with experimental values.

Relativistic correlating basis sets for the sixth-period d-block atoms from Lu to Hg.

Contracted Gaussian-type function sets to describe valence correlation are developed for the sixth-period d-block atoms Lu through Hg. A segmented contraction scheme is employed for their compactness and efficiency. Contraction coefficients and exponents are determined by minimizing the deviation from accurate natural orbitals generated from configuration interaction calculations, in which relativistic effects are incorporated through the third-order Douglas-Kroll approximation. The present basis sets yield more than 99% of atomic correlation energies predicted by accurate natural orbital sets of the same size. Relativistic model core potential calculations with the present correlating sets give the spectroscopic constants of the AuH molecule in excellent agreement with experimental results.