Density Functional Theory Study of Rh_nS^0,± and Rh_n+1^0,± (n = 1–9)

Abstract

A basin-hopping search strategy has been used to determine likely candidates for low-energy Rh(n)S(0,±) (n = 1-9) cluster structures. Cluster structures were optimized at the density functional level of theory using the PBE and PBE0 functionals. Ionization energies, electron detachment energies, HOMO-LUMO gap energies, UV-visible spectra, low-lying fragmentation channels and energies, cluster structures, spin multiplicities, and vibrational spectra are predicted for Rh(n)S(0,±) and Rh(n+1)(0,±) (n = 1-9). Donation from valence sulfur atomic p orbitals to valence rhodium atomic d orbitals and back-donation to valence sulfur atomic d orbitals leads to electron density delocalization and metal-like behavior for rhodium sulfide clusters.

Studying Gas-Phase Interconversion of Tautomers Using Differential Mobility Spectrometry

“…To understand how ion/solvent clusters in the post-DMS region may be involved in such an HDX "relay mechanism," we performed basin hopping (BH) searches of the potential energy landscape for (4-ABA•H + )(CH 3 OH) n (n = 1-8) clusters [43][44][45]. As a result, we identified three different structural motifs: N-protonated, O-protonated, and solvent-bridged.…”

“…First, the basin-hopping (BH) search algorithm was used to identi fy t he low -energy i som ers of (4-ABA•H + )(CH 3 OH) n (n = 1-8) clusters [43][44][45]. This search employed the AMBER molecular mechanics force field and partial charges for each monomer as calculated at the B3LYP/ 6-31+G(d,p) level of theory using the CHelpG partition scheme [46][47][48][49].…”

Infrared-Driven Charge Transfer in Transition Metal B12F12 Clusters

“…This supports the chemically intuitive view that the metal centers retain a high partial positive charge for these ground state clusters. Second order perturbation theory analysis of the Fock matrix in the NBO basis facilitates calculation of the dominant interactions associated with the transfer of charge density to the metal cation 45,46. These are summarized for Ag(I)•B 12 F 12 ] ─ .…”

Augmenting Basin-Hopping With Techniques From Unsupervised Machine Learning: Applications in Spectroscopy and Ion Mobility

“…Molecular global optimization (GO) to identify the chemically-relevant species on hypergeometric potential energy surfaces (PESs) provides both rationalizations and predictions of experimental observations by relating thermodynamic and kinetic properties to the accessible local minima and the transition states (TSs) that connect them (Scheraga, 1992; Piela et al, 1994; Wales and Doye, 1997; Wales and Scheraga, 1999). Basin-hopping (BH) is a technique for GO that is based on the iterative approach of performing random perturbation of geometric coordinates, local optimization of a model potential energy function, and accepting or rejecting the perturbed coordinates based on the value of the minimized function (Wales and Doye, 1997; Wales et al, 1998; Wales and Scheraga, 1999; Lecours et al, 2014). Use of the BH algorithm for searching molecular PESs was outlined by Wales and Doye in their 1997 article “Global Optimization by Basin-Hopping and the Lowest Energy Structures of Lennard-Jones Clusters Containing up to 110 Atoms,” (Wales and Doye, 1997) which describes how the technique transforms the PES into a collection of interpenetrating staircases wherein each stair/plateau on the transformed surface is associated with a stationary point (usually local minimum) of the original potential energy landscape.…”

“…To further improve the efficiency of a BH search, one can include additional criteria for assessment of distorted molecular geometries prior to optimization. For example, one might choose to reject structures in which inter-atomic distances are less than some pre-defined threshold, or one might choose to define an interaction volume to prevent molecular/cluster dissociation (Lecours et al, 2014). It is also common to select specific degrees of freedom (DoFs) for random distortion while freezing others; one might choose to search the conformational space defined by molecular dihedral angles while leaving the distances between chemically bonded atoms fixed (Hopkins et al, 2013, 2015).…”