Polynitrogen molecules and ions are important building blocks of high energy density compounds (HEDCs). High bonds formed at the N sites can be effectively probed by X-ray photoelectron spectroscopy (XPS) K-edge. In this work, with functional theory ΔKohn-Sham scheme, we simulated N1s ionic potentials (IPs) 72 common polynitrogen [tetrazoles, pentazole (N5H), diazines, triazines, tetrazines, furazans, oxazoles oxadiazoles], [pentazolate anion (cyclo-N5-), pentazenium cation (N5+), etc.],...

Under the Franck-Condon approximation, we systematically validated performance of density functional theory (DFT) and effects anharmonicity in simulating C, N, O $K$-edge vibrationally resolved x-ray spectra common diatomic molecules cations. To get ``transparent'' validations, vibronic fine structures only lowest $1s$ excited or ionized state absorption spectroscopy (XAS) photoelectron (XPS) were investigated. All six systems $({\mathrm{N}}_{2}, {\mathrm{N}}_{2}^{+}, \mathrm{NO},...

Vibronic coupling plays a crucial role in x-ray photoelectron spectra (XPS) of molecules. In series three papers, we present comprehensive exploration the $N$-heterocycles family, known for their diverse structures, to summarize general rules vibronic high-resolution vibrationally resolved XPS at N $1s$ edge. Building upon our previous studies on six-membered monocyclic azines [Phys. Rev. A 106, 022811 (2022)] and fused bicyclic compounds indoles with five six members 108, 022816 (2023)],...

Proton transfer (PT) in organic crystals creates localized charges and strong hydrogen bonding (HB), making the self-consistent field (SCF) calculation of core-ionized core-excited states challenging. Today most corresponding X-ray spectral measurements are interpreted based on empirical fitting and/or chemical intuitions. Here we present a systematic quantum mechanical/molecular mechanical (QM/MM) study N 1s photoelectron (XPS) absorption (XAS) spectra three isonicotinamide (IN)-based with...

The structure of cyclo[18]carbon (C$_{18}$), whether in its polyynic form with bond length alternation (BLA) or cumulenic without BLA, has long fascinated researchers, even prior to successful synthesis. Recent studies suggest a ground state and transient state; however, the dynamics remain unclear lack experimental validation. This study presents first-principles theoretical investigation lengths ($R_1$ $R_2$) dependent two-dimensional potential energy surfaces (PESs) C$_{18}$,...

The vibronic coupling effect in nitrogen $1s$ x-ray photoelectron spectra was systematically studied for a family of 17 bicyclic indole molecules by combining Franck-Condon simulations (including the Duschinsky rotation effect) and density-functional theory. simulated vibrationally resolved four agree well with available experiments. Reliable predictions this further allows us to summarize rules spectral evolution response three types common structural changes (side chain substitution,...

X-ray absorption spectroscopy (XAS) is widely employed for structure characterization of graphitic carbon nitride (g-C3N4) and its composites. Nevertheless, even pure g-C3N4, discrepancies in energy profile exist across different experiments, which can be attributed to variations structures arising from diverse synthesis conditions calibration procedures. Here, we conducted a theoretical investigation on XAS three representative g-C3N4 (planar, corrugated, micro-corrugated) optimized with...

Vibrationally resolved C 1s X-ray photoelectron spectra (XPS) of a series six polycyclic aromatic hydrocarbons (PAHs; phenanthrene, coronene, naphthalene, anthracene, tetracene, and pentacene) were computed by combining the full core hole density functional theory Franck–Condon simulations with inclusion Duschinsky rotation effect. Simulated naphthalene agree well experiments both in binding energies (BEs) profiles, which validate accuracy our predictions for rest molecules no...

Truncated cluster models represent an effective way for simulating x-ray spectra of 2D materials. Here, we systematically assessed the influence two key parameters, shape (honeycomb, rectangle, or parallelogram) and size, in photoelectron (XPS) absorption (XAS) simulations three materials at five K-edges (graphene, C 1s; C3N, C/N h-BN, B/N 1s) to pursue accuracy limit binding energy (BE) spectral profile predictions. Several recent XPS experiments reported BEs with differences spanning 0.3,...

Vibronic coupling plays a pivotal role in molecular spectroscopy. We present theoretical study on vibrationally resolved x-ray photoelectron spectra (XPS) of seven azines (${\mathrm{C}}_{x}{\mathrm{H}}_{y}{\mathrm{N}}_{z}$; pyridine, three diazines, two triazines, and one tetrazine) at the nitrogen $1s$ edge, to explore vibronic effects as influenced by consecutive replacement CH group with N atom. Franck-Condon simulations were performed Duschinsky rotation effect included, where electronic...

Understanding proton transfer (PT) dynamics in condensed phases is crucial chemistry. We computed a 2D map of N 1s X-ray photoelectron/absorption spectroscopy (XPS/XAS) for an organic donor-acceptor salt crystal against two varying N-H distances to track motions. Our results provide continuous spectroscopic mapping O-H···N↔O

Carbonyl groups (C=O) play crucial roles in the photophysics and photochemistry of biological systems. O1s x-ray photoelectron spectroscopy allows for targeted investigation C=O group, coupling between vibration ionization is reflected fine structures. To elucidate its characteristic vibronic features, systematic Franck–Condon simulations were conducted six common biomolecules, including three purines (xanthine, caffeine, hypoxanthine) pyrimidines (thymine, 5F-uracil, uracil). The complexity...

Vibronic coupling plays a crucial role in X-ray photoelectron spectra (XPS) of molecules. In series three papers, we present comprehensive exploration the N-heterocycles family, known for their diverse structures, to summarize general rules vibronic high-resolution vibrationally-resolved XPS at N1s edge. Building upon our previous studies on six-membered monocyclic azines [Phys. Rev. A 106, 022811 (2022)] and fused bicyclic compounds indoles with five six members 108, 022816 (2023)], this...

Understanding the proton transfer dynamics through hydrogen bonds is a fundamental issue in chemistry, especially condensed phases. While time-resolved X-ray spectroscopy offers unique probe localized within bonds, accurate interpretation remains challenge and relies on high-quality theoretical spectral references that map motions. Here, with hybrid quantum mechanical molecular (QM/MM) simulations, we computed two-dimensional (2D) of N1s photoelectron/absorption spectra (XPS/XAS) for an...

Purines and pyrimidines, crucial building blocks in biological systems, have attracted significant interest across molecular physics, biochemistry, pharmacology, chemistry. Extensive spectroscopies been employed for characterization, while the temperature potential tautomeric effects can complicate interpretation of underlying physics Here, we conducted first-principles simulations to analyze vibrationally-resolved O1s X-ray photoelectron spectra 6 common biomolecules at different...

X-ray absorption spectroscopy (XAS) is widely employed for structure characterization of graphitic carbon nitride (g-C$_3$N$_4$) and its composites. Nevertheless, even pure g-C$_3$N$_4$, discrepancies in energy profile exist across different experiments, which can be attributed to variations structures arising from diverse synthesis conditions calibration procedures. Here, we conducted a theoretical investigation on XAS three representative g-C$_3$N$_4$ (planar, corrugated, micro-corrugated)...

We integrated full core-hole density functional theory with Franck-Condon calculations, considering Duschinsky rotation, to simulate vibrationally-resolved C1s X-ray photoelectron spectra (XPS) of eight linear alkanes, from methane octane (C$_{n}$H$_{2n+2}$, $n$=1--8). Results align excellently experimental absolute binding energies and profiles. The spectrum ethane serves as a ``spectral seed'', each longer alkane's atom-specific displaying similar characteristics, albeit shifts slight...

We integrate full core-hole density-functional theory with Franck-Condon calculations, considering Duschinsky rotation, to simulate vibrationally resolved C $1s$ x-ray photoelectron spectra of eight linear alkanes, from methane octane (${\mathrm{C}}_{n}{\mathrm{H}}_{2n+2}, n=1--8$). Results align excellently experimental absolute binding energies and profiles. The spectrum ethane serves as a ``spectral seed,'' each longer alkane's atom-specific displaying similar characteristics, albeit...

High-resolution X-ray spectroscopy is an essential tool in astronomy, enabling detailed studies of celestial objects and their physical chemical properties. However, comprehensive mapping high-resolution spectra for even simple interstellar circumstellar molecules still lacking. In this study, we conducted systematic quantum simulations to predict the C1s absorption CN$^+$, CN, CN$^-$. Our findings provide valuable references both astronomy laboratory studies. We assigned first electronic...

The vibronic coupling effect in nitrogen 1s X-ray photoelectron spectra (XPS) was systematically studied for a family of 17 bicyclic indole molecules by combining Franck-Condon simulations (including the Duschinsky rotation effect) and density functional theory. simulated vibrationally-resolved 4 agree well with available experiments. Reliable predictions this further allowed us to summarize rules spectral evolution response three types common structural changes (side chain substitution,...

Under the Franck-Condon approximation, we systematically validated performance of density functional theory (DFT) and effects anharmonicity in simulating C/N/O K-edge vibrationally-resolved X-ray spectra common diatomic molecules. To get ``transparent'' validations, vibronic fine structures only lowest 1s excited or ionized state absorption (XAS) photoelectron (XPS) were investigated. All 6 systems (N$_2$, N$_2^+$; NO, NO$^+$; CO, CO$^+$) studied within harmonic oscillator (HO) approximation...