Atomic And Molecular Clusters

---

Compound-tunable embedding potential method and its application to fersmite crystal (1907.06947v1)

D. A. Maltsev, Yu. V. Lomachuk, V. M. Shakhova, N. S. Mosyagin, L. V. Skripnikov, A. V. Titov

2019-07-16

Compound-tunable embedding potential (CTEP) method is proposed. A fragment of some chemical compound, "main cluster" in the present paper, is limited by boundary anions such that the nearest environmental atoms are cations. The CTEP method is based on constructing the embedding potential as linear combination of short-range "electron-free" spherical "tunable" pseudopotentials for cations from nearest environment of the main cluster, whereas the long-range CTEP part consists of Coulomb potentials from optimized fractional point charges centered on both environmental cations and anions. A pilot application of the CTEP method to the fersmite crystal, CaNbO, is performed and a remarkable agreement of the electronic density and interatomic distances within the fragment with those of the original periodic crystal calculation is attained. Characteristics of "atoms-in-compounds" which are of great importance for compound of - and -elements (Nb in fersmite) are considered on examples of chemical shifts of and lines of X-ray emission spectra in niobium. A very promising potential of this approach in studying variety of properties of point defects containing - and heavy -elements with relativistic effects, extended basis set and broken crystal symmetry considered is discussed.

Setting the photoelectron clock through molecular alignment (1802.06622v2)

Andrea Trabattoni, Joss Wiese, Umberto De Giovannini, Jean François Olivieri, Terry Mullins, Jolijn Onvlee, Sang-Kil Son, Biagio Frusteri, Angel Rubio, Sebastian Trippel, Jochen Küpper

2018-02-19

The interaction of strong laser fields with matter intrinsically provides powerful tools to image transient dynamics with an extremely high spatiotemporal resolution. In strong-field physics, the initial conditions of this interaction are generally considered a weak perturbation. We investigated strong-field ionisation of laser-aligned molecules and showed, for the first time, a full real-time picture of the photoelectron dynamics in the combined action of the laser field and the molecular interaction. We demonstrated that the molecule defines the initial conditions of the photoelectron at birth and has a dramatic impact on the overall strong-field recollision dynamics: it sets the clock for the emission of electrons with a given rescattering kinetic energy. This result represents a new benchmark for the seminal statements of molecular-frame strong-field physics. Our findings have strong impact on the interpretation of self-diffraction experiments, where the photoelectron momentum distribution is used to retrieve molecular structures. Furthermore, the resulting encoding of the time-energy relation in molecular-frame photoelectron distributions shows the way of probing the molecular potential in real-time and accessing a deeper understanding of electron transport during strong-field interactions.

Electron capture and ionization cross-section calculations for proton collisions from methane and the DNA and RNA nucleobases (1907.06708v1)

Hans Juergen Luedde, Marko Horbatsch, Tom Kirchner

2019-07-15

Net ionization and net capture cross-section calculations are presented for proton collisions from methane molecules and the DNA/RNA nucleobases adenine, cytosine, guanine, thymine, and uracil. We use the recently introduced independent-atom-model pixel counting method to calculate these cross sections in the 10 keV to 10 MeV impact energy range and compare them with results obtained from the simpler additivity rule, a previously used complete-neglect-of-differential-overlap method, and with experimental data and previous calculations where available. It is found that all theoretical results agree reasonably well at high energies, but deviate significantly in the low-to-intermediate energy range. In particular, the pixel counting method which takes the geometrical overlap of atomic cross sections into account is the only calculation that is able to describe the measurements for capture in proton-methane collisions down to 10 keV impact energy. For the nucleobases it also yields a significantly smaller cross section in this region than the other models. New measurements are urgently required to test this prediction.

The most stable isomer of HC-(OCS) van der Waals complex: Theory and experiment agree on a structure with C2 symmetry (1907.05822v1)

A. J. Barclay, A. Pietropolli Charmet, N. Moazzen-Ahmadi

2019-07-12

We report the infrared spectrum of HC-(OCS) trimer in the region of the nu1 fundamental vibration of the OCS monomer. The van der Waals complexes are generated in a supersonic slit-jet apparatus and probed using a rapid-scan tunable diode laser. Both HC-(OCS) and DC-(OCS) are studied. Analysis of their spectra establishes that the trimer has C point group symmetry. Theoretical calculations performed to find stationary points on the potential energy surface confirm that the observed structure is the most stable form. The experimental rotational parameters are in very good agreement with those computed using double hybrid functionals.

Photoemission from hybrid states of Cl@ before and after a stabilizing charge transfer (1907.04881v1)

Dakota Shields, Ruma De, Mohamed El-Amine Madjet, Steven T. Manson, Himadri S. Chakraborty

2019-07-10

Photoionization calculations of the endofullerene molecule Cl@ with an open-shell chlorine atom are performed in the time-dependent local density approximation (TDLDA) based on a spherical jellium model. Cross sections for atom-fullerene hybrid photoemission studied show the effects of the hybridization symmetry, the giant plasmon and the molecular cavity. Comparisons with the results of Ar@ provide insights in the role of a shell-closing electron and its influence on the dynamics. The results for Cl@ are further compared with those of a more stable, lower energy configuration that results after a electron transfers to Cl forming Cl@. This comparison reveals noticeable differences in the ionization properties of the antibonding hybrid state while the bonding hybrid remains nearly unaltered showing a magnification covering the entire giant plasmon energy range.

Far-from-equilibrium dynamics of angular momentum in a quantum many-particle system (1906.12238v2)

Igor N. Cherepanov, Giacomo Bighin, Lars Christiansen, Anders Vestergaard Jørgensen, Richard Schmidt, Henrik Stapelfeldt, Mikhail Lemeshko

2019-06-28

We use laser-induced rotation of single molecules embedded in superfluid helium nanodroplets to reveal angular momentum dynamics and transfer in a controlled setting, under far-from-equilibrium conditions. As an unexpected result, we observe pronounced oscillations of time-dependent molecular alignment that have no counterpart in gas-phase molecules. Angulon theory reveals that these oscillations originate from the unique rotational structure of molecules in He droplets and quantum-state-specific transfer of rotational angular momentum to the many-body He environment on picosecond timescales. Our results pave the way to understanding collective effects of macroscopic angular momentum exchange in solid state systems in a bottom-up fashion.

Pure Molecular Beam of Water Dimer (1904.08716v3)

Helen Bieker, Jolijn Onvlee, Melby Johny, Lanhai He, Thomas Kierspel, Sebastian Trippel, Daniel A. Horke, Jochen Küpper

2019-04-18

Spatial separation of water dimer from water monomer and larger water-clusters through the electric deflector is presented. A beam of water dimer with purity and a rotational temperature of K was obtained. Following strong-field ionization using a fs laser pulse with a wavelength centered around nm and a peak intensity of we observed proton transfer and of the ionized water dimer broke apart into a hydronium ion and neutral OH.

Structure determination of the tetracene dimer in helium nanodroplets using femtosecond strong-field ionization (1907.03168v1)

Constant Schouder, Adam S. Chatterley, Florent Calvo, Lars Christiansen, Henrik Stapelfeldt

2019-07-06

Dimers of tetracene molecules are formed inside helium nanodroplets and identified through covariance analysis of the emission directions of kinetic tetracene cations stemming from femtosecond laser-induced Coulomb explosion. Next, the dimers are aligned in either one or three dimensions under field-free conditions by a nonresonant, moderately intense laser pulse. The experimental angular covariance maps of the tetracene ions are compared to calculated covariance maps for seven different dimer conformations and found to be consistent with four of these. Additional measurements of the alignment-dependent strong-field ionization yield of the dimer narrows the possible conformations down to either a slipped-parallel or parallel-slightly-rotated structure. According to our quantum chemistry calculations, these are the two most stable gas-phase conformations of the dimer and one of them is favorable for singlet fission.

Electronic structure of 3-transition-metal monoxide anions from calculations: ScO, TiO, CuO, and ZnO (1907.02181v1)

Young-Moo Byun, Serdar Öğüt

2019-07-04

The approximation to many-body perturbation theory is a reliable tool for describing charged electronic excitations, and it has been successfully applied to a wide range of extended systems for several decades using a plane-wave basis. However, the approximation has been used to test limited spectral properties of a limited set of finite systems (e.g. frontier orbital energies of closed-shell molecules) only for about a decade using a local-orbital basis. Here, we calculate the quasiparticle spectra of closed- and open-shell molecular anions with partially and completely filled 3 shells (i.e. with shallow and deep 3 states), ScO, TiO, CuO, and ZnO, using various levels of theory, and compare them to experiments to evaluate the performance of the approximation on the electronic structure of small molecules containing 3 transition metals. We find that the -only eigenvalue-only self-consistent scheme with fixed to the PBE level (@PBE), which gives the best compromise between accuracy and efficiency for solids, also gives good results for both localized () and delocalized () states of transition metal oxide molecules. The success of @PBE in predicting electronic excitations in these systems reasonably well is likely due to the fortuitous cancellation effect between the overscreening of the Coulomb interaction by PBE and the underscreening by the neglect of vertex corrections. Together with the absence of the self-consistent field convergence error (e.g. due to spin contamination in open-shell systems) and the multi-solution issue, the @PBE scheme gives the possibility to predict the electronic structure of complex real systems (e.g. molecule-solid and - hybrid systems) accurately and efficiently.

Reexamination of Tolman's law and the Gibbs adsorption equation for curved interfaces (1703.08719v2)

Martin Thomas Horsch, Stefan Becker, Michaela Heier, Jayant Kumar Singh, Felix Diewald, Ralf Müller, George Jackson, Jadran Vrabec, Hans Hasse

2017-03-25

In manuscript arXiv:1703.08719 [cond-mat.soft], it was claimed that the well-known deduction of Tolman's law is not rigorous, since Tolman's argument implies that two different definitions of the surface tension, called and in the manuscript, coincide. This claim is retracted as it can be shown by free-energy minimization that indeed holds for the Laplace radius. Joachim Gro\ss, Philipp Rehner, Carlos Vega, \O{}ivind Wilhelmsen, and the anonymous reviewers of The Journal of Chemical Physics contributed to finding the mistake in the manuscript.

---

Keeping updated in the latest research in atomic and molecular clusters!