for a simple connected graph $g$ with $n$-vertices having laplacian eigenvalues‎ ‎$mu_1$‎, ‎$mu_2$‎, ‎$dots$‎, ‎$mu_{n-1}$‎, ‎$mu_n=0$‎, ‎and signless laplacian eigenvalues $q_1‎, ‎q_2,dots‎, ‎q_n$‎, ‎the laplacian-energy-like invariant($lel$) and the incidence energy ($ie$) of a graph $g$ are respectively defined as $lel(g)=sum_{i=1}^{n-1}sqrt{mu_i}$ and $ie(g)=sum_{i=1}^{n}sqrt{q_i}$‎. ‎in th...

In this paper we explore the use of the novel relativistic intermediate Hamiltonian Fock-space coupled-cluster method in the calculation of the electronic spectrum for small actinyl ions (NpO2+, NpO2(2+), and PuO2(2+)). It is established that the method, in combination with uncontracted double-zeta quality basis sets, yields excitation energies in good agreement with experimental values, and be...

The observation of long-lived electronic quantum coherence in a photosynthetic light harvesting system [Engel et al. Nature 2007, 446, 782] has led to much effort being devoted to elucidation of the quantum mechanisms of the photosynthetic excitation energy transfer. In this paper we examine the question of whether the decay of the coherent beating signal is due to quantum mechanical decoherenc...

The Hilbert-Huang transform is applied to analyze single-particle Lagrangian velocity data from numerical simulations of hydrodynamic turbulence. The velocity trajectory is described in terms of a set of intrinsic mode functions C(i)(t) and of their instantaneous frequency ω(i)(t). On the basis of this decomposition we define the ω-conditioned statistical moments of the C(i) modes, named q-orde...

We present here a detailed time-dependent density-functional theory investigation aimed at systematically dissecting the electronic spectra of two thiolate and phosphine protected undecagold nanoclusters. Calculations performed on the experimental structures of Au11(PPh3)7Cl3 and Au11(PPh3)7(SPyr)3 show that ligands have negligible contributions in the visible region. Metal → ligand charge tran...

The CP29 light harvesting complex from green plants is a pigment-protein complex believed to collect, conduct, and quench electronic excitation energy in photosynthesis. We have spectroscopically determined the relative angle between electronic transition dipole moments of its chlorophyll excitation energy transfer pairs in their local protein environments without relying on simulations or an X...

Coherence oscillations measured in two-dimensional (2D) electronic spectra of pigment-protein complexes may have electronic, vibrational, or mixed-character vibronic origins, which depend on the degree of electronic-vibrational mixing. Oscillations from intrapigment vibrations can obscure the inter-site coherence lifetime of interest in elucidating the mechanisms of energy transfer in photosynt...

Structures and spectra are calculated for Si(n) and Si(n)-Gly (n = 3-5) complexes. Relative stability differences of Gly conformers are magnified by interactions with the Si(n) cluster, so that one conformer of Si(n)-Gly is stabilized. Significant charge transfer occurs from the amino group in Gly to a Si atom in the cluster. Interactions with Gly are predicted to shift the excitation energies ...

The calculation of the vibrational structure associated to electronic spectra in large molecules requires a Taylor expansion of the initial and final state potential energy surface (PES) around some reference nuclear structure. Vertical (V) and adiabatic (A) approaches expand the final state PES around the initial-state (V) or final-state (A) equilibrium structure. Simplest models only take int...

Excited-state geometries and electronic spectra of butadiene, acrolein, and glyoxal have been investigated by the symmetry adapted cluster configuration interaction (SAC-CI) method in their s-trans conformation. Valence and Rydberg states below the ionization threshold have been precisely calculated with sufficiently flexible basis sets. Vertical and adiabatic excitation energies were well repr...