Triangulenes are a class of open‐shell triangular graphene flakes with total spin increasing with their size. In the last years, on‐surface‐synthesis strategies have permitted fabricating and engineering triangulenes of various sizes and structures with atomic precision. However, direct proof of the increasing total spin with their size remains elusive. In this work, we report the combined in‐solution and on‐surface synthesis of a large nitrogen‐doped triangulene (aza‐[5]‐triangulene) on a Au(111) surface, and the detection of its high‐spin ground state. Bond‐resolved scanning tunneling microscopy images uncovered radical states distributed along the zigzag edges, which were detected as weak zero‐bias resonances in scanning tunneling spectra. These spectral features reveal the partial Kondo screening of a high‐spin state. Through a combination of several simulation tools, we find that the observed distribution of radical states is explained by a quintet ground state (S=2), instead of the quartet state (S=3/2) expected for the neutral species. This confirms that electron transfer to the metal substrate raises the spin of the ground state. We further provide a qualitative description of the change of (anti)aromaticity introduced by N‐substitution, and its role in the charge stabilization on a surface, resulting in an S=2 aza‐triangulene on Au(111).

Using density functional theory combined with an evolutionary algorithm for crystal structure prediction, we study the elastic and electronic properties of various multi-principal element alloys that are based on CoCrFeNi. In total, nine quinary and one senary CoCrFeNiX ($\mathrm{X}=\mathrm{Ti}$ , V, Mn, MnV, Cu, Zr, Nb, Mo, Al, Al${}_2$ ) alloys are studied along with the base CoCrFeNi alloy. The aim of the current study is twofold. First, we test and confirm the ability of the presented methodology to predict the crystal structure of the multi-principal element alloys based on Co, Cr, Fe, and Ni elements. Second, we calculate and compare the elastic properties of the CoCrFeNiX alloys, as well as their electronic properties, in an attempt to establish possible correlations between them. Taking CoCrFeNi as the reference alloy, our first-principles calculations of various elastic moduli (bulk, Young, and shear moduli) show that only the bulk moduli of the alloys with Cu, Mo, or Nb (in this order) are expected to be larger. Furthermore, our comparative analysis of the CoCrFeNiX alloys containing partially filled 3$d$ and 4$d$ elements shows that the filling of the $d$ -shell causes a general increase in all the elastic moduli. The only exception is the decreasing behavior of the bulk modulus in the case of alloys with partially filled 3$d$ elements.

The aim of this work is to study the microstructure of four high entropy alloys (HEAs) produced by large scale vacuum die casting. Al₄₀Cu₁₅Mn₅Ni₅Si₂₀Zn₁₅, Al₄₅Cu₁₅Mn₅Fe₅Si₅Ti₅Zn₂₀, Al₃₅Cu₅Fe₅Mn₅Si₃₀V₁₀Zr₁₀, and Al₅₀Ca₅Cu₅Ni₁₀Si₂₀Ti₁₀ alloys formed a mixture of different structures, containing intermetallic compound (IC) and solid solution (SS) phases. The phases observed in the casting alloys were compared with the equilibrium phases predicted by Thermo-Calc. The measured densities varied from 3.33 g/cm⁻³ to 5.07 g/cm⁻³ and microhardness from 437 Hv to 887 Hv. Thus, the microhardness and estimated strength/density ratios are significantly higher than other lightweight high entropy alloys (LWHEAs).

The self-consistent electron–ion potential V ( r ) is calculated for H ⁺ ions in an electron gas system as a function of the projectile energy to model the electronic stopping power for conduction-band electrons. The results show different self-consistent potentials at low projectile-energies, related to different degrees of excitation of the electron cloud surrounding the intruder ion. This behavior can explain the abrupt change of velocity dependent screening-length of the potential found by the use of the extended Friedel sum rule and the possible breakdown of the standard free electron gas model for the electronic stopping at low projectile energies. A dynamical interpolation of V ( r ) is proposed and used to calculate the stopping power for H ⁺ interacting with the valence electrons of Al. The results are in good agreement with the TDDFT benchmark calculations as well as with experimental data.

We present a combined theoretical and experimental study of the energy loss of ${\mathrm{H}}_2{}^{+}$ molecular ions interacting with thin oxide and carbon films. As a result of quantum mechanical interference of the target electrons, the energy loss of a molecular projectile differs from the sum of the energy losses of individual atomic projectiles. This difference is known as the vicinage effect. Calculations based on the time-dependent density functional theory allow the first-principles description of the dynamics of target excitations produced by the correlated motion of the nucleons forming the molecule. We investigate in detail the dependence of the vicinage effect on the speed and charge state of the projectile and find an excellent agreement between calculated and measured data.