Atomic and Molecular Clusters
The question whether the linear absorption spectra of metal clusters can be interpreted as density oscillations (collective ``plasmons'') or can only be understood as transitions between distinct molecular states is still a matter of debate…
A variational wave function constructed with correlated Hyperspherical Harmonic functions is used to describe the Helium trimer. This system is known to have a deep bound state. In addition, different potential models predict the existence…
The multipole response of $^3$He$_N$ drops doped with very attractive impurities, such as a Xe atom or an SF$_6$ molecule, has been investigated in the framework of the Finite Range Density Functional Theory and the Random Phase…
We study the interaction of strong femtosecond laser pulses with the C$_{60}$ molecule employing time-dependent density functional theory with the ionic background treated in a jellium approximation. The laser intensities considered are…
The fission of highly charged sodium clusters with fissilities X>1 is studied by {\em ab initio} molecular dynamics. Na_{24}^{4+} is found to undergo predominantly sequential Na_{3}^{+} emission on a time scale of 1 ps, while Na_{24}^{Q+}…
We report on results of a theoretical study of the adsorption process of a single carbon oxide molecule on a Platinum (111) surface. A four-component relativistic density functional method was applied to account for a proper description of…
We find that for simple metal clusters a single-electron description of the ground state employing self-interaction correction (SIC) in the framework of local-density approximation strongly contaminates the high energy photoionization cross…
A partial differential eigenvalue equation for the density displacement fields associated with electronic excitations is derived in the framework of density functional theory. Our quantum fluid-dynamical approach is based on a variational…
The properties of neutral and anionic Pd_N clusters were investigated with spin-density-functional calculations. The ground state structures are three-dimensional for N>3 and they are magnetic with a spin-triplet for 2<=N<=7 and a spin…
The scattering of ortho positronium (Ps) by H$_2$ has been investigated using a three-Ps-state [Ps(1s,2s,2p)H$_2($X $^1\Sigma_g^+$)] coupled-channel model and using Born approximation for higher excitations and ionization of Ps and B…
We study the thermodynamics of Na_8 and Na_{20} clusters using multiple-histogram methods and an ab initio treatment of the valence electrons within density functional theory. We consider the influence of various electron kinetic-energy…
The energetic characteristics of two-shell carbon nanoparticles ("onions") with different shapes of second shell are calculated. The barriers of relative rotation of shells are found to be surprisingly small; therefore, free relative…
The emergence of CsCl bulk structure in (CsCl)nCs+ cluster ions is investigated using a mixed quantum-mechanical/semiempirical theoretical approach. We find that rhombic dodecahedral fragments (with bulk CsCl symmetry) are more stable than…
We determined the ionic and electronic structure of sodium clusters with even electron numbers and 2 to 59 atoms in axially averaged and three-dimensional density functional calculations. A local, phenomenological pseudopotential that…
The melting-like transition in potasium clusters K_N, with N=20, 55, 92 and 142, is studied by using an orbital-free density-functional constant-energy molecular dynamics simulation method, and compared to previous theoretical results on…
The melting-like transition in disordered sodium clusters Na_N, with N=92 and 142 is studied by using a first-principles constant-energy molecular dynamics simulation method. Na_142, whose atoms are distributed in two (surface and inner)…
We have developed a transferable nonorthogonal tight-binding total energy model for germanium and use it to study small clusters. The cohesive energy, bulk modulus, elastic constants of bulk germanium can be described by this model to…
We have performed classical trajectory Monte Carlo (CTMC) studies of electron capture and ionization in multiply charged (Q=8) ion-Rydberg atom collisions at intermediate impact velocities. Impact parallel to the minor and to the major…
The electronic structure of C_(4N+2) carbon rings exhibits competing many-body effects of Huckel aromaticity, second-order Jahn-Teller and Peierls instability at large sizes. This leads to possible ground state structures with aromatic,…
The thermal expansion coefficients of $\mathrm{Na}_{N}$ clusters with $8 \le N \le 40$ and $\mathrm{Al}_{7}$, $\mathrm{Al}_{13}^-$ and $\mathrm{Al}_{14}^-$ are obtained from {\it ab initio} Born-Oppenheimer LDA molecular dynamics. Thermal…