Calculated Dipole Moments Research Articles

The Effect of Sulphur Atoms on the Structure of Biomolecule 2-Thiocytosine in the Gas-Phase, Solid-State, and Hydrated Forms and in DNA–DNA Microhelices as Compared to Canonical Ones

This study is focused on the effects of the sulphur atom in position 2 of the cytosine molecule, 2-thiocytosine (2TC), on the molecular structural parameters in the isolated state, as well as in the hydration, solid state arrangement, Watson–Crick pairs, and DNA–DNA microhelices, as compared to the canonical form. The main six tautomers were optimised at the MP2 and CCSD levels, and the sulphur atom does not show any effect on the stability trend of cytosine. The energy difference between T2b and T2a tautomers is twice as low in 2TC (1.15 kJ/mol) than in cytosine (2.69 kJ/mol). The IR and laser Raman spectra of 2TC were accurately assigned using DFT computations and solid-state simulations of the crystal unit cell through several tetramer forms. The results notably improve those previously published by other authors. The effect of explicit water molecules surrounding 2TC up to 30, corresponding to the first and second hydration shells, on geometries and tautomerism was analysed. The Watson–Crick base pairs’ stability (ΔECP = −97.458 kJ/mol) was found to be less than with cytosine (−105.930 kJ/mol). The calculated dipole moment was also lower (4.205 D) than with cytosine (5.793 D). The effect of 2TC on the 5′-dG-dC-dG-3′ and 5′-dA-dC-dA-3′ DNA–DNA optimised microhelices was evaluated through their calculated helical parameters, which indicates a clear deformation of the helix formation. The radius (R) with 2TC appears considerably shorter (6.200 Å) in the 5′-dA-dC-dA-3′ microhelix than that with cytosine (7.050 Å). Because of the special characteristics of the 2TC molecule, it can be used as an anticancer drug.

Highly accurate real-space electron densities with neural networks.

Variational abinitio methods in quantum chemistry stand out among other methods in providing direct access to the wave function. This allows, in principle, straightforward extraction of any other observable of interest, besides the energy, but, in practice, this extraction is often technically difficult and computationally impractical. Here, we consider the electron density as a central observable in quantum chemistry and introduce a novel method to obtain accurate densities from real-space many-electron wave functions by representing the density with a neural network that captures known asymptotic properties and is trained from the wave function by score matching and noise-contrastive estimation. We use variational quantum Monte Carlo with deep-learning Ansätze to obtain highly accurate wave functions free of basis set errors and from them, using our novel method, correspondingly accurate electron densities, which we demonstrate by calculating dipole moments, nuclear forces, contact densities, and other density-based properties.

Quadrupole Moment of a Magnetically Confined Mountain on an Accreting Neutron Star in General Relativity

Abstract General relativistic corrections are calculated for the quadrupole moment of a magnetically confined mountain on an accreting neutron star. The hydromagnetic structure of the mountain satisfies the general relativistic Grad–Shafranov equation supplemented by the flux-freezing condition of ideal magnetohydrodynamics, as in previous calculations of the magnetic dipole moment. It is found that the ellipticity, and hence the gravitational wave strain, are up to 12% greater than in the analogous Newtonian system. The direct contribution of the magnetic field to the nonaxisymmetric component of the stress-energy tensor is shown to be negligible in accreting systems such as low-mass X-ray binaries.

Evaluating the Anticancer Properties of Novel Piscidinol A Derivatives: Insights from DFT, Molecular Docking, and Molecular Dynamics Studies.

Cancer is characterized by uncontrolled cell growth and spreading throughout the body. This study employed computational approaches to investigate 18 naturally derived anticancer piscidinol A derivatives (1-18) as potential therapeutics. By examining their interactions with 15 essential target proteins (HIF-1α, RanGAP, FOXM1, PARP2, HER2, ERα, NGF, FAS, GRP78, PRDX2, SCF complex, EGFR, Bcl-xL, ERG, and HSP70) and comparing them with established drugs such as camptothecin, docetaxel, etoposide, irinotecan, paclitaxel, and teniposide, compound 10 emerged as noteworthy. In molecular dynamics simulations, the protein with the strongest binding to the crucial 1A52 protein exceeded druglikeness criteria and displayed extraordinary stability within the enzyme's pocket over varied temperatures (300-320 K). Additionally, density functional theory was used to calculate dipole moments and molecular orbital characteristics, as well as analyze the thermodynamic stability of the putative anticancer derivatives. This finding reveals a well-defined, potentially therapeutic relationship supported by theoretical analysis, which is in good agreement with subsequent assessments of their potential in vitro cytotoxic effects of piscidinol A derivatives (6-18) against various cancer cell lines. Future in vivo and clinical studies are required to validate these findings further. Compound 10 thus emerges as an intriguing contender in the fight against cancer.

Antimicrobial, and Antitubercular Evaluation with ADME and Molecular Docking Studies and DFT Calculatıons of (Z)-3-((1-(5-amino-1,3,4-thiadiazol-2-yl)-2-Phenylethyl)imino)-5-nitroindolin-2-one Schiff Base

(Z)-3-((1-(5-Amino-1,3,4-Thiadiazol-2-yl)-2-Phenylethyl)İmino)-5-nitroindolin-2-one Schiff Base compound (ATSB) have lately gained popularity, so the concept that these compounds should be researched has been highlighted. ATSB molecule, a unique Schiff base complex, was selected for molecular modeling research for publication in the literature. Initially, dependent density functional theory (DFT) computations were performed on ATSB molecule (geometry optimization, HOMO-LUMO, MEPS maps, dipole moment calculations, NBO analysis, and Mulliken Atomic Charges). Additionally, ADME analyzes have been carried out for the ATSB molecule and the color regions are given separately. Schiff bases have been shown to have an important role in antibacterial and antituberculosis medication illness and drug repair. Finally, in our investigation, molecular docking analysis ments were performed individually for ATSB molecule with two distinct enzymes (5V3X and 5V3Y), docking scores and receptor models have been given.

Dual-Vacancy-Engineered ZnIn2S4 Nanosheets for Harnessing Low-Frequency Vibration Induced Piezoelectric Polarization Coupled with Static Dipole Field to Enhance Photocatalytic H2 Evolution

This study delves into the realm of chemically complex materials, focusing on Zinc Indium Sulfide (ZnIn2S4, ZIS) for efficient photocatalytic water splitting into hydrogen (H2) and oxygen (H2). Recognizing the pivotal role of microstructures in chemically complex materials, our research emphasizes the impact of defects in ZIS, a material with multiple principal chemical components, on its H2 production efficiency. We explore the optimization of material defects, particularly sulfur (S) and indium (In) vacancies, under external stress to enhance H2 production through dipole and piezoelectric effects. To unravel the intricate process-structure-property relationships in ZIS, we utilize a multi-scale computational approach. Density Functional Theory (DFT) is employed to calculate dipole moment, dielectric, elastic, and piezoelectric properties under varying defect compositions. These properties are then integrated into a continuum model developed through Finite Element Analysis (FEA), bridging mechanical and electrical phenomena to simulate the electric potential distribution (voltage) in both pristine and defective ZIS. Our simulations demonstrate a marked increase in voltage, induced by internal dipole moments and piezoelectric effects, especially pronounced along the (100) and (010) crystal orientations in defective ZIS. This enhanced voltage leads to improved charge separation, substantially increasing the H2 production rate upon electron excitation and generation of electron/hole pairs. Our findings contribute vital insights into the microstructural influences on the photocatalytic performance of ZIS, offering design principles for advanced materials in renewable energy applications. This study exemplifies the power of computational techniques in elucidating the complex interplay between microstructure and properties in chemically complex materials, aligning with the core focus of this symposium. Figure 1

Visible Opacities of S-type Stars: The d 3Φ–a 3Δ Band System of ZrO

ZrO is a well-studied metal monoxide because of its astrophysical importance in characterizing S stars. The bands of the d 3Φ–a3Δ system (γ system) with v′≤4 and v″ ≤ 5 are rotationally analyzed using the PGOPHER program to provide spectroscopic constants. The high-resolution ZrO emission spectrum was recorded with a Fourier transform spectrometer using a high-temperature carbon furnace source. New ab initio calculations of the transition dipole moment were carried out in order to determine the vibronic band strengths. The spectroscopic constants, along with the band strengths, are used to calculate a line list for the γ system. This line list can be used to determine Zr abundances in S stars. We also correct the line strengths for the B 1Π–A 1Δ transition calculated in our previous work.

The analysis of sarcosine phosphate single crystal based on polarized IR and Raman spectra

For the first time, the room temperature polarized IR reflection and Raman spectra of sarcosine phosphate (sar)·H3PO4, in the form of an oriented single crystal have been measured. The polarized spectra are discussed with respect to the crystal structure (X-ray diffraction) data and the literature data on the normal coordinate analysis of the zwitterionic and cationic forms of the sarcosine molecule. Based on the analysis of the spectra and transition dipole moment calculations for each internal mode with respect to the experimental X(a), Y(b) and Z(c) axes, we have been able to determine the directionality and strength of the complicated hydrogen bonds network in the crystal. The A-B-C band structure of the OH stretching vibrations in the strongest hydrogen bonds (HBs) has been assigned. Independent interactions of each HB with light are confirmed based on their polarization properties. The differences within the band of carboxyl group components are ascribed to a rather strong Davydov-type interaction between the carboxyl groups in the title crystal, they may also be caused by participation of the carboxyl-oxygen atom in the medium-strong HB with phosphate-oxygen. These studies are interesting from the point of view of designing strategy for the molecular engineering of new compounds with strong hydrogen bonds, new phase-change materials, as well as crystals with improved optical, magnetic and nonlinear optical properties.

Space and laboratory discovery of iminopentadienylidene, HNC5

We report the discovery of HNC$_5$ in TMC-1. Six lines have been found in harmonic relation, with quantum numbers $J$=12-11 up to $J$=17-16. The lines can be reproduced with the standard frequency relation for linear molecules with $B$=1361.75034pm 0.00033 MHz and $D$=32.2pm 0.7 Hz. The assignment of the carrier to iminopentadienylidene was achieved through examining the possible candidates at a high level of theoretical ab initio calculations. Motivated by the good agreement between the observed $B$ and the calculated value for HNC$_5$, we searched for it in the laboratory and observed the transitions $J$=5-4 to 7-6. The derived rotational and distortion constants are 1361.74998pm 0.00040 MHz and 26.5pm 5.5 Hz, respectively. Hence, we solidly conclude that the carrier of the lines found in TMC-1 is HNC$_5$. The calculated dipole moment for this species is 7.7\,D and the derived column density is (1.3pm 0.2)times 1010 $. We used the new QUIJOTE data to improve previous observations of HC$_4$NC and found that the abundance ratio HC$_4$NC/HNC$_5$ is 10pm 2. The abundance ratio of HC$_5$N and its two isomers HC$_4$NC and HNC$_5$ is 500pm 80 and 5100pm 800, respectively. These abundance ratios are higher by a factor of sim 10 than those of the equivalent isomers of HC$_3$N. Chemical models reproduce the observed abundances reasonably well when a chemistry similar to that of the smaller species C$_3$HN isomers is adopted. The formation of HNC$_5$ and HC$_4$NC arises from the dissociative recombination with electrons of the cations HC$_5$NH$^+$ and HC$_4$NCH$^+$.

Theoretical evaluation of C24 nanocage functionalization with protons for enhanced sulfacetamide drug delivery: A DFT study with non-covalent interaction analyses

In the realm of drug design, achieving precise and effective drug delivery poses a significant challenge. In this computational study, we explore the capacity of pristine C24 nanocages and those modified with 1H+ and 2H+ ions to serve as carriers for the sulfacetamide (SA) drug, employing density functional theory (DFT) calculations. Geometry optimizations of the SA&C24, SA&H+C24, and SA&2H+C24 complexes were conducted at the cam-B3LYP/6–31+G (d, p) level of theory. The optimized structures of all complexes exhibit local minima on the potential energy surface, indicated by the absence of imaginary frequencies, which confirms their thermodynamic stability. The negative values of adsorption energy (Eads) denote an exothermic and favorable adsorption process, with H+ ion functionalization enhancing the drug's binding affinity to the nanocages. Further analysis of the structural properties of the complexes was conducted through natural bond orbital (NBO) charge distribution, dipole moment calculations, and frontier molecular orbital analysis. Additionally, Atoms in Molecules (AIM), reduced density gradient (RDG), and electron localization function (ELF) analyses were employed to elucidate the nature of intermolecular interactions governing the drug-nanocage binding. UV-visible and nonlinear optical (NLO) response calculations reveal the potential of both pristine and functionalized C24 nanocages as optical sensors for SA drug detection. Our findings suggest that these nanocages hold promise for the development of sensitive drug delivery vehicles and targeted therapeutic agents.

Theoretical investigation of the electronic structure of the Rhodium Halides molecules RhF and RhCl with dipole moment calculation

The current study involves an ab initio exploration of the ground and low-lying excited electronic states of the rhodium halide molecules RhF and RhCl using the complete active space self-consistent field (CASSCF) with multireference configuration interaction (MRCI+Q) method including single and double excitations and with Davidson corrections. We investigated the potential energy curves, the transition and permanent electric dipole moments, the electronic energy relative to the ground state Te, the harmonic frequency ωe, the internuclear distance Re, and the rotational constant Be corresponding to each of the bounded states. Our findings demonstrate good agreement with the available experimental data. Notably, this work represents the inaugural theoretical investigation of the excited states of RhF and RhCl molecules, identifying the ground state of both to be X3Π, as observed in the sole two experimental investigations.

Molecular self-assembled helix peptide nanotubes based on some amino acid molecules and their dipeptides: molecular modeling studies.

The paper considers the features of the structure and dipole moments of several amino acids and their dipeptides which play an important role in the formation of the peptide nanotubes based on them. The influence of the features of their chirality (left L and right D) and the alpha-helix conformations of amino acids are taken into account. In particular, amino acids with aromatic rings, such as phenylalanine (Phe/F), and branched-chain amino acids (BCAAs)-leucine (Leu/L) and isoleucine (Ile/I)-as well as corresponding dipeptides (diphenylalanine (FF), dileucine (LL), and diisoleucine (II)) are considered. The main features and properties of these dipeptide structures and peptide nanotubes (PNTs), based on them, are investigated using computational molecular modeling and quantum-chemical semi-empirical calculations. Their polar, piezoelectric, and photoelectronic properties and features are studied in detail. The results of calculations of dipole moments and polarization, as well as piezoelectric coefficients and band gap width, for different types of helical peptide nanotubes are presented. The calculated values of the chirality indices of various nanotubes are given, depending on the chirality of the initial dipeptides-the results obtained are consistent with the law of changes in the type of chirality as the hierarchy of molecular structures becomes more complex. The influence of water molecules in the internal cavity of nanotubes on their physical properties is estimated. A comparison of the results of these calculations by various computational methods with the available experimental data is presented and discussed. The main tool for molecular modeling of all studied nanostructures in this work was the HyperChem 8.01 software package. The main approach used here is the Hartree-Fock (HF) self-consistent field (SCF) with various quantum-chemical semi-empirical methods (AM1, PM3, RM1) in the restricted Hartree-Fock (RHF) and in the unrestricted Hartree-Fock (UHF) approximations. Optimization of molecular systems and the search for their optimal geometry is carried out in this work using the Polak-Ribeire algorithm (conjugate gradient method), which determines the optimized geometry at the point of their minimum total energy. For such optimized structures, dipole moments D and electronic energy levels (such as EHOMO and ELUMO), as well as the band gap Eg = ELUMO - EHOMO, were then calculated. For each optimized molecular structure, the volume was calculated using the QSAR program implemented also in the HyperChem software package.

Molecules in Cool Stars: The A2Π − X2Σ+ and the B2Σ+ − X2Σ+ Band Systems of CaCl

Cool red giant stars exhibit absorption bands of calcium monochloride (CaCl) in the optical region. In this work, the bands of CaCl corresponding to the A2Π − X2Σ+ transition with v′≤ 4 and v″ ≤ 4, and B2Σ+ − X2Σ+ transition with v′≤ 2 and v″ ≤ 2 are rotationally analyzed with PGOPHER, a multipurpose program for simulating and fitting molecular spectra. All bands were analyzed using high-resolution absorption spectra collected at the National Solar Observatory in 1985, calibrated with atomic lines from a high-resolution emission spectrum obtained in a separate hollow cathode experiment. The results are compared with previous laser-induced fluorescence measurements. Overall, the accuracy of spectroscopic constants for the A2Π and B2Σ+ states is improved. Scaled transition dipole moment calculations were used to obtain line strengths. Line lists are provided with Einstein A coefficients and oscillator strengths, which can be used to determine CaCl stellar abundances. Additionally, isotope splittings allowed us to estimate band origins for the 40Ca37Cl isotopologue based on band-head positions.

SLIMP 2.0: A new version of strong laser interaction model package for atoms and molecules, now with molecular orbital tomography based on high-order harmonic spectra

A new version of strong laser interaction model package for atoms and molecules is presented. Its capacities are enhanced by incorporating modules related to molecular orbital tomography (MOT) in length and velocity forms based on high-order harmonic spectra (HHS). This advanced package enables two-dimensional and three-dimensional MOT of both symmetric and asymmetric molecules using HHS, providing an efficient means for both experimental and theoretical investigations of molecular orbital structures. In addition, it can calculate the precise theoretical orbitals corresponding to those reconstructed by MOT. Furthermore, the package can calculate the transition dipole moment (TDM) in the plane wave approximation and allow for reference MOT based on TDM. It can evaluate the quality of reconstructed orbitals based on HHS and reveal the physical and numerical effects on MOT. This package is suitable for MOT under conditions of driving laser at different intensities and wavelengths, and can be applied to different molecules with various structures. It is designed to facilitate easy expansion for additional capabilities. Program summaryProgram Title: SLIMP, version 2.0CPC Library link to program files:https://doi.org/10.17632/jgcb7m7wwv.1Licensing provisions: GPLv3Programming language: Fortran 90Journal reference of previous version: Comput. Phys. Commun. 192 (2015) 330-341.Does the new version supersede the previous version?: Yes.Reasons for the new version: Molecular orbital tomography (MOT) [1] based on high-order harmonic spectra (HHS) [2] is an important research topic in the field of strong-field physics. It provides an efficient way to probe molecular orbital structures experimentally, which was not considered in the former version of SLIMP [3] and is now included in SLIMP 2.0. The new version package allows performing two-dimensional (2D) and three-dimensional (3D) MOT [4] based on HHS obtained from experiments or simulations, providing reliable detections for many orbitals of interest, either symmetric or asymmetric molecules.Summary of revisions: Extending capacities focus on enabling performing 2D and 3D MOT on symmetric and asymmetric molecules based on HHS, and together the relevantly precise theoretical orbital output, calculation of transition dipole moment (TDM) and reference MOT based on TDM. For 2D MOT, MOT in both length and velocity forms are implemented.Nature of problem: To perform MOT based on HHS, the user needs general reconstruction programs, taking symmetric and asymmetric molecules, 2D and 3D orbitals, and MOT in length and velocity forms into account. In addition, evaluation of imaging quality is required, which can reveal the physical and numerical effects on reconstructions.Solution method: The 2D symmetric and asymmetric, length- and velocity-form, and 3D reconstruction algorithms are implemented based on Fortran 90. Furthermore, this package provides a reference MOT based on directly calculated TDM, served as a comparable result to the reconstructed orbital based on HHS. The comparison between reconstructions based on HHS and TDM can reveal the effects on MOT in physical and numerical aspects.Additional comments including restrictions and unusual features: This package does not include MOT of asymmetric molecules in velocity form. For the 2D MOT based on HHS, the reconstructed 2D projection of gerade, ungerade orbital or the gerade and ungerade components of asymmetric orbital must have the axial symmetry about the x- and z-axis. For the 3D MOT, the reconstructed 3D orbital has to be cylindrically symmetric.

Theoretical investigation of the silver chalcogenide molecules AgSe and AgTe electronic structure with dipole moment calculation

The spectroscopic constants (Re, Te, ωe, Be) are determined for 46 doublet and quartet low-lying states of the molecules AgTe and AgSe using CASSCF/MRCI (single and double excitations plus Davidson correction) calculations. The equilibrium bond length Re, and the vibrational frequency ωe of the ground state of both molecules have also been investigated using the density functional theory (DFT) incorporating eight different functionals along with different basis sets. The potential energy and permanent dipole moment curves of 23 states of each molecule have been investigated and depicted. This study represents the first theoretical investigation of the molecules AgSe and AgTe.

Diamond two-phonon infrared absorption spectrum calculated from first principles using the finite displacement method

We calculate the two-phonon contribution to the dielectric susceptibility of diamond at room and elevated temperatures, utilizing a general ab initio model that can be extended to higher n phonon processes. We calculate the second-order dipole moments using a finite displacement method to calculate the derivatives of the Born effective charge tensor. Specifically, we use results obtained from density-functional theory and density-functional perturbation theory in this finite displacement method to calculate the dipole moments of diamond in the two-phonon case. We use the calculated dipole moment to determine the contribution of two-phonon processes to the dielectric susceptibility. We then calculate the absorption curve as a function of wave-number at room or elevated temperatures. Our results indicate that the calculated absorption is in good agreement with previous calculations, and that it increases in magnitude with temperature while maintaining a consistent shape.

Resolving the Anisotropic Dynamical Evolution of Wide Bandgap GeSe2 Under Polarized Photoexcitation

AbstractGermanium diselenide (GeSe2) has recently emerged as a promising material for high‐performance optoelectronic devices due to its high absorption coefficient, wide direct bandgap, and anisotropic electronic properties. For the future applications, it is necessary to understand the dynamic evolution of carriers with ultrafast response. In this work, the transient absorption spectroscopy measurements are performed to study the anisotropic dynamic evolution of GeSe2 under the polarized photoexcitation. It is find that the dynamics exhibit linear dichroism and show a significant Auger recombination process when the photoexcitation is perpendicular to the b‐axis of GeSe2. Using first‐principle and transition dipole moment calculations, it is confirmed that the more carrier localization at Γ point along the Γ‐X (perpendicular to the b‐axis) and increase the Auger recombination. In addition, the Auger recombination coefficient ≈ 1.1×10−31 cm6 s−1 is determined and demonstrated that the defect‐assisted indirect Auger recombination plays a key role in the carrier relaxation process. Through time‐resolved transient absorption spectra, it is further revealed that the ultrafast dynamical evolution of excited state absorption peaks under polarized photoexcitation. These results have implications for improving the quantum efficiency of high‐field polarization‐sensitive optoelectronics.

Mitochondria Play Essential Roles in Intracellular Protection against Oxidative Stress-Which Molecules among the ROS Generated in the Mitochondria Can Escape the Mitochondria and Contribute to Signal Activation in Cytosol?

Questions about which reactive oxygen species (ROS) or reactive nitrogen species (RNS) can escape from the mitochondria and activate signals must be addressed. In this study, two parameters, the calculated dipole moment (debye, D) and permeability coefficient (Pm) (cm s-1), are listed for hydrogen peroxide (H2O2), hydroxyl radical (•OH), superoxide (O2•-), hydroperoxyl radical (HO2•), nitric oxide (•NO), nitrogen dioxide (•NO2), peroxynitrite (ONOO-), and peroxynitrous acid (ONOOH) in comparison to those for water (H2O). O2•- is generated from the mitochondrial electron transport chain (ETC), and several other ROS and RNS can be generated subsequently. The candidates which pass through the mitochondrial membrane include ROS with a small number of dipoles, i.e., H2O2, HO2•, ONOOH, •OH, and •NO. The results show that the dipole moment of •NO2 is 0.35 D, indicating permeability; however, •NO2 can be eliminated quickly. The dipole moments of •OH (1.67 D) and ONOOH (1.77 D) indicate that they might be permeable. This study also suggests that the mitochondria play a central role in protecting against further oxidative stress in cells. The amounts, the long half-life, the diffusion distance, the Pm, the one-electron reduction potential, the pKa, and the rate constants for the reaction with ascorbate and glutathione are listed for various ROS/RNS, •OH, singlet oxygen (1O2), H2O2, O2•-, HO2•, •NO, •NO2, ONOO-, and ONOOH, and compared with those for H2O and oxygen (O2). Molecules with negative electrical charges cannot directly diffuse through the phospholipid bilayer of the mitochondrial membranes. Short-lived molecules, such as •OH, would be difficult to contribute to intracellular signaling. Finally, HO2• and ONOOH were selected as candidates for the ROS/RNS that pass through the mitochondrial membrane.

Conditions for the efficiency of optical limiting based on experiment and quantum chemical calculations.

The development of suitable protection against laser radiation has proven challenging due to the lack of predictive models. The purpose of this article is to exclude the existing drawback by creating a universal strategy based on correlations between experimental and theoretical data characterizing the nonlinear optical properties of absorbers, for which a series of low-symmetry penta(chloro)cyclotriphosphazene-substituted monophthalocyanines was chosen. To search for correlations on a small series of dyes, we used the advanced algorithm CORRELATO, which has been proven to construct even the most unusual relationships demonstrated in our previous works. Due to the reducing symmetry of molecules, large values of the nonlinear absorption coefficient (more than 3000 cm GW-1) and, as a result, wide dynamic ranges (up to 630) with a high degree of attenuation of nanosecond laser radiation (10-20 times) were achieved. The use of the finite-field DFT method has allowed the calculation of dipole moments, polarizabilities and hyperpolarizabilities. The numerical data obtained during the calculations were used in correlations of theory vs. experiment to derive mathematical expressions (inequalities) to assess the effectiveness of absorbers in limiting the power of laser radiation.

Opacities of S-type Stars: The Singlet B 1Π–X 1Σ+, B 1Π–A 1△, and C 1Σ+–X 1Σ+ Band Systems of ZrO

The ZrO B 1Π–X 1Σ+, B 1Π–A 1Δ, and C 1Σ+–X 1Σ+ band systems are important opacity sources in the near-infrared and optical spectra of S-type stars. A total of 21 rovibronic bands with v″ ≤ 7 and were observed and fit for the B 1Π–X 1Σ+ transition, five bands for the 90ZrO B 1Π–A 1Δ transition and one band for the 90ZrO C 1Σ+–X 1Σ+ transition. All band systems were analyzed using high-temperature, high-resolution emission spectra collected at the National Solar Observatory (Kitt Peak). A modern spectroscopic analysis was performed using the PGOPHER program to provide updated spectroscopic constants. In general, we improve the accuracy of the line positions reported in the literature and slightly extend the vibrational analysis. Equilibrium molecular constants were then derived and combined with new ab initio calculations of transition dipole moment functions to produce line lists with line strengths.