# Franco A GianturcoSapienza University of Rome | la sapienza · Department of Chemistry

Franco A Gianturco

## About

479

Publications

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Citations since 2017

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January 1988 - December 2013

January 1974 - December 1989

## Publications

Publications (479)

We report for the first time an accurate ab initio potential energy surface for the HeH+-H2 system in four dimensions (4D) treating both diatomic species as rigid rotors. The computed ab initio potential energy point values are fitted using an artificial neural network method and used in quantum close coupling calculations for different initial sta...

By extending an earlier study [Gianturco et al., J. Chem. Phys. 154, 054311 (2021)] on the purely rotational excitation of HeH⁺ by He atoms, we report in this paper integral cross sections and rate coefficients for rovibrational excitation and de-excitation processes in HeH⁺ due to collisions with He. The data were obtained using a new ab initio po...

The scattering cross-sections and corresponding rate coefficients for rotationally inelastic collisions of 12C2− (2Σg+) with H2 (1Σg+) are presented over a broad range of cold-trap temperatures. They have been calculated using quantum scattering theory that employs a new ab initio potential energy surface. The rate coefficients for the inelastic pr...

Ab initio calculations are employed to generate the rigid rotor (RR) potential energy surface (PES) describing the interaction of the linear molecular cation HeHHe+, at its equilibrium geometry, with the neutral He atom. The resulting interaction is employed to investigate the efficiency of rotational state-changing collisions at the temperatures r...

Two different ab initio potential energy surfaces are employed to investigate the efficiency of the rotational excitation channels for the polar molecular ion HeH⁺ interacting with He atoms. We further use them to investigate the quantum dynamics of both the proton-exchange reaction and the purely rotational inelastic collisions over a broad range...

The potential energy surfaces for C�2(2Sþg) interacting with He, Ne and Ar are calculated usingab initioquantum chemistry methods. The PES are used to carry out coupled-channel quantum scattering cal-culations for the three systems to obtain the rotationally inelastic scattering cross sections from whichthe rotationally inelastic state-changing rat...

We present in this paper the main structural features and enthalpy details for the energy profiles of the title reactions, both for the exothermic (forward) path to NH$_{3}$ formation and for the endothermic (reverse) reaction to NH$_{2}^{-}$ formation. Both systems have relevance for the nitrogen chemistry in the interstellar medium (ISM). They ar...

Using the ab initio computed Potential Energy Surface (PES) for the electronic interaction of the MgH$^+$ ($^1\Sigma$) ion with the He($^1$S) atom, we calculate the relevant state-changing rotationally inelastic collision cross sections from a quantum treatment of the multichannel scattering problem. We focus on the quantum dynamics at the translat...

We present a computational investigation of the photodetachment (PD) dynamics of C 2 H ⁻ in its ground, electronic ¹ Σ state, cooled in an ion trap with He as a buffer gas. Our analysis employs a range of PD rates from quantum dynamics, selective choices of the anion’s initial rotational state populations as the laser is switched on, and different...

We present a theoretical study of rotationally elastic and inelastic collisions between molecular nitrogen ions and Rb atoms in the sub-Kelvin temperature regime prevalent in ion-atom hybrid trapping experiments. The cross sections for rotational excitation and de-excitation collisions were calculated using quantum-scattering methods on ab initio p...

We present a theoretical study of rotationally elastic and inelastic collisions between molecular nitrogen ions and Rb atoms in the sub-Kelvin temperature regime prevalent in ion-atom hybrid trapping experiments. The cross sections for rotational excitation and de-excitation collisions were calculated using quantum-scattering methods on ab-initio p...

Using accurate ab initio calculations of the interaction forces, we employ a quantum mechanical description of the collisional state-changing processes that occur in a cold ion trap with He as a buffer gas. We generate the corresponding inelastic rates for rotational transitions involving three simple molecular anions OH⁻(¹Σ), MgH⁻(¹Σ), and C2H⁻(¹Σ...

Using the ab initio computed potential energy surface for the electronic interaction of the MgH+(Σ1) ion with the He(S1) atom, we calculate the relevant state-changing rotationally inelastic collision cross sections from a quantum treatment of the multichannel scattering problem. We focus on the quantum dynamics at the translationally low energies...

Multichannel scattering calculations are presented for the low-energy collisions of the OH⁺ cation and He atoms, using an ab initio evaluation of the interaction potential, which had been obtained in earlier work, and a time-independent, multichannel treatment of the quantum dynamics carried out in this study using our in-house scattering code ASPI...

We construct the velocity map images of the proton transfer reaction between helium and molecular hydrogen ions H + 2. We perform simulations of imaging experiments at one representative total collision energy taking into account the inherent aberrations of the velocity mapping in order to explore the feasibility of direct comparisons between theor...

We investigate the relative efficiencies of low-temperature chemical reactions in the interstellar medium with H⁻ anion reacting in the gas phase with cyanopolyyne neutral molecules, leading to the formation of anionic linear chains of different lengths and of H2. All the reactions turn out to be without barriers, highly exothermic reactions that p...

In the present paper we analyze in detail several properties of the MgH− anion and the MgH neutral molecule using accurate ab initio quantum computational methods in order to establish with a higher reliability specific molecular features like the gas-phase electron affinity, the Franck-Condon factors for excitation of the neutral and of its anion...

Accurate state-to-state rovibrational inelastic collisional cross sections involving the smallest molecular anion astronomically detected with He(¹S) based on two recently computed energy surfaces will be presented. A detailed comparison between the collisional findings provided either using a high-level of accuracy in the potential energy surface...

We present a detailed computational analysis for the interaction between the vibrating/rotating molecular ions H2⁺, HD⁺, D2⁺ colliding with He atoms employed as buffer gas within ion trap experiments. The production and preparation of these molecular ions from their neutrals usually generate rovibrationally excited species which will therefore requ...

Precision vibrational spectroscopy of the molecular hydrogen ions is of significant interest for determining fundamental constants, for searching for new forces, and for testing quantum electrodynamics calculations. Future experiments can profit from the ability of preparing molecular hydrogen ions at ultralow kinetic energy and in preselected inte...

We report in the present study a quantum analysis of the collisional dynamics involving a negative ion, LiH⁻ in its ²Σ⁺ ground electronic state, and He as a buffer gas in the environment of cold ion traps. The work focuses on the evaluation of the internal cooling collisional rates, treating both the anion's rotational quantum numbers and the spin-...

(abridged) The fairly recent detection of a variety of anions in the Interstellar Molecular Clouds have underlined the importance of realistically modeling the processes governing their abundance. To this aim, our earlier calculations for the radiative electron attachment (REA) rates for C4H-, C6H-, and C8H- are employed to generate the correspondi...

The nucleophilic substitution reaction CN- + CH3I allows for two possible reactive approaches of the reactant ion onto the methyl halide, which lead to two different product isomers. Stationary point calculations predict a similar shape of the potential and a dominant collinear approach for both attacks. In addition, an H-bonded pre-reaction comple...

Calculations are reported for electron and positron scattering from isolated cytosine and thymine, where the two pyrimidinic single-ring DNA bases, in the gas-phase at energies near the elastic threshold, they reveal the special features of the dipole-driven scattering states. All molecules examined exhibit, in fact, supercritical (>1.67 D) permane...

Variational calculations (T = 0 K) on small HeN...He*- and HeN...He2*- metastable clusters (N?4), as well as Path Integral Monte Carlo (PIMC) simulations (T = 0.4 K) on larger species are presented and discussed.

We employ an accurate, ab initio potential energy surface (PES) which describes the electronic interaction energy between the molecular anion OH− ( ) and the neutral rubidium atom Rb ( ), to evaluate the elastic and inelastic cross sections over a range of energies representative of the conditions of low-T experiments in MOT traps, when combined wi...

The barrierless, exothermic reactions of H - with HCnN cyanopolyynes, with n = 1 and 3, are analyzed using ab initio calculations of the interaction forces. The shape of the reactive potential energy surface suggests the most efficient approach of H - to be on a nearly collinear arrangement on the H-side of HCnN. Using simple transition state formu...

The possibility of attaching near-threshold electrons to N-terminated carbon chains, like those observed in the outer envelopes of carbon-rich stars, is examined via accurate quantum chemistry orbital structures evaluation and quantum scattering analysis of the corresponding extra-electron wavefunctions at meV energies. It is shown that the differe...

Quantum scattering calculations are presented for the interaction of low energy positrons with the uracil molecule, an important component of biological systems. The rotational elastic and inelastic cross sections and vibrational inelastic cross sections are reported and compared with existing experiments, indicating a general trend of the cross se...

The existence of metastable anions, formed in the gas-phase by electron scattering off anthracene molecules is investigated via both quantum dynamics calculations and quantum chemical structure calculations. The differences in the sign of the experimentally known electron affinity (EA), positive small for anthracene, and of its values obtained from...

We discuss in some detail the implications of the suggestion made by P D Burrow and G A Gallup on the physics of anion formation and of resonant electron attachment in gas-phase anthracene molecules.

The possible losses of silicon atom population during star-forming
evolution and in the (photon-dominated region) PDR environments of the
interstellar medium (ISM) can have different origins, one being the
charge exchange (CE) encounter with the helium cations (Si +
He+) one of the most abundant species in those environments.
This work investigates...

In this paper we report new quantum calculations of the dynamics for low-energy positrons interacting with gaseous molecules of tetrahydrofuran. The new quantum scattering cross sections are differential and integral cross sections at collision energies between 1.0 and 25.0 eV and include a careful treatment of the additional effects on the scatter...

Chemistry plays a key role in many astrophysical situations regulating the cooling and the thermal properties of the gas,
which are relevant during gravitational collapse, the evolution of discs and the fragmentation process. In order to simplify
the usage of chemical networks in large numerical simulations, we present the chemistry package krome,...

In the present work we are reporting detailed quantum scattering calculations that describe the diffusion of a beam of low-energy positrons interacting with the pyrimidine target as a gas-phase partner. The calculations have employed an essentially ab initio model for the short-range correlation interaction and for the electrostatic interaction of...

The lowest two potential energy surfaces which involve Mg+(2P) and Mg+(2S) atoms interacting with H2 molecules are computed to describe both the intermediate complex [MgH ] formed during their reactive approaches and the asymptotic outcomes of MgH+ + H or of Mg+ + H2. The calculations clearly reveal the presence of an avoided crossing between the t...

The elementary mechanisms through which molecular polyynes could form stable negative ions after interacting with free electrons in planetary atmospheres (e.g., Titan's) are analyzed using quantum scattering calculations and quantum structure methods. The case of radical species and of nonpolar partners are analyzed via specific examples for both t...

We present new, accurate quantum calculations of the reaction rates of
methyldyne depleted by hydrogen atoms for temperature ranging from 10 K to 1000
K. Although a wide range of calculations have been presented over the years on
the chemistry of CH+, no final assessment for this reaction has been given in
the literature. In this study, the negativ...

Doped HeN
Rb2 (3Σ
u
+) systems, with N = 20 and 40, have been studied by means of a path integral Monte Carlo method at two different temperatures T = 1 K and 2 K. The impurity, Rb2, is assumed as a rigid rotor and results are compared with a previous analysis in which no rotational or translational degrees of freedom were taken into account. Quant...

We present scattering calculations of electron collisions with the platinum-containing compound cis-diamminedichloroplatinum (CDDP), commonly known as cisplatin, between 0.5 eV and 6 eV, and the corresponding isolated Pt atom from 0.1 eV to 10 eV. We find evidence of resonances in e(-)-CDDP scattering, using an ab initio description of the target....

The quantum dynamics of free electrons interacting with diacetylene molecules (HCCCCH) under the conditions observed in planetary atmospheres (like those of Titan and Uranus) is analyzed using two different ab initio interaction and multichannel scattering methods as described in the main text. The locations of π
∗ and σ
∗ resonances, and their spa...

We present ab initio calculations for the dissociative recombination rates of LiHe+ ions. The study involves first a realistic understanding of the electronic structure of the ion and neutral LiHe molecule and then carrying out the nuclear dynamics the system undergoes during the dissociation process. For the electronic part we employ R-matrix calc...

We report a computational investigation of electron scattering by anthracene (C(14)H(10)) in the gas phase. Integral and differential cross sections have been calculated by employing two distinct ab-initio quantum scattering methods: the symmetry adapted-single centre expansion method (ePOLYSCAT) and a screening corrected form of the independent at...

Quantum mechanical scattering calculations are carried out for gas-phase molecules of anthracene, an aromatic system with three condensed aromatic carbon rings, in collision with low-energy electrons. They reveal the presence of various metastable (resonant) anionic states of this prototype species belonging to the larger polycondensed aromatic hyd...

The present work focuses on the reaction of a molecule of astrophysical interest, the HeH+, with the most abundant species in the Universe: the H atom, and in situations where the partner ion is internally excited into some of its lower rotational states. This strongly exothermic reaction: HeH++H→H2++He, leads to the destruction of HeH+ and we stud...

Diffusion and path integral Monte Carlo methods are currently, and successfully, used to describe structures and binding energies of helium clusters doped with some impurity. For diatomic dopants, by considering the He atoms as "electrons" and the dopant as "nuclei" within a Hartree/Hartree-Fock framework, our group has developed a complementary to...

Chemistry has a key role in the evolution of the interstellar medium (ISM),
so it is highly desirable to follow its evolution in numerical simulations.
However, it may easily dominate the computational cost when applied to large
systems. In this paper we discuss two approaches to reduce these costs: (i)
based on computational strategies, and (ii) b...

The time-dependent rate coefficients for the charge exchange reaction C+ + Si → C + Si+ for doublet and quartet states have been determined with ab initio quantum calculations coupled with a non-adiabatic transition
model based on a simple Landau–Zener picture. This reaction plays a key role in determining the abundances of C, Si and their
ions, in...

We report theoretical integral and differential cross sections for electron scattering from hydrogen cyanide derived from two ab initio scattering potential methods. For low energies (0.1-100 eV), we have used the symmetry adapted-single centre expansion method using a multichannel scattering formulation of the problem. For intermediate and high en...

Bound states of 40Ca-nHe2, n=3,4,
triatomic complexes are investigated. The potential-energy surface,
represented as the addition of atomic-pair interactions, is that
recently used to study these systems by Gou and Li, Phys. Rev.
APLRAAN1050-294710.1103/PhysRevA.85.012510 85, 012510 (2012). The
results obtained from three different methods, in fair...

We discuss the computational results on the energetics and features of the bound states of one and two He atoms attached to a Ca atom, which have been presented by Gou and Li in a recently published paper in Phys. Rev. A 85, 012510 (2012). We show that, given their choice for the interaction potential-energy surface, the energy they found for the t...

The formation of anionic species in the interstellar medium from interaction
of linear molecules containing carbon, nitrogen and hydrogen as atomic
components (polyynes) with free electrons in the environment is modelled via a
quantum treatment of the collision dynamics. The ensuing integral cross
sections are employed to obtain the corresponding a...

CONTEXT: The attachment of free electrons to polycondensed aromatic ring
molecules (PAHs) is studied for the variety of these molecules with different
numbers of condensed rings and over a broad range of electron temperatures,
using a multichannel quantum scattering approach. The calculations of the
relevant cross sections are used in turn to model...

We present in this paper binding energies and structures of non-rotating weakly bound 40Ca–n
He2 triatomic complexes. Two kind of systems are discussed: bosonic (n = 4) and fermionic (n = 3) complexes at its singlet state (nuclear spin S = 0). Three different coordinate systems and methods have been used to solve the relevant Schrödinger equation:...

Multichannel quantum scattering calculations are employed to investigate the low-energy (E coll ≤ 7 eV) region of the interaction between gas-phase neutral coronene and environmental electrons in interstellar clouds. The presence of several resonance features is revealed by our calculations and their symmetry characterization is also reported. Thei...

Diffusion Monte Carlo (DMC), after Variational Monte Carlo (VMC), calculations are carried out to assess the possible binding and the spatial collocation of the negatively charged LiH− molecule as a single dopant in small clusters of 4He. The number of cluster adatoms is extended to N=15 and the bosonic, quantum solvent is found to stabilize as a n...

We present a new computational scheme aimed at reducing the complexity of the
chemical networks in astrophysical models, one which is shown to markedly
improve their computational efficiency. It contains a flux-reduction scheme
that permits to deal with both large and small systems. This procedure is shown
to yield a large speed-up of the correspon...

A path integral Monte Carlo method has been used to study small (4He)N–Rb2(3Σu+) complexes at low temperatures. We focus our investigation on the range 1 K ⩽ T ⩽ 2 K for aggregates of different sizes containing between 10 and 40 helium atoms. The extremely weak He–Rb2 interaction, with a shallower potential depth and a longer equilibrium bond lengt...

Nonadiabatic inelastic collision cross sections have been computed at low and ultralow energies, focusing in the present work on the Ca + (4s 2 S) + Rb(5s 2 S) → Ca(4s4p 3 P) + Rb + (1 S) charge-exchange process at ultralow collision energies (E 10 −6 eV) induced by spin-orbit nonadiabatic coupling terms. The calculations reveal a wealth of sharp r...

In the present paper we analyse in some detail the possible nuclear deformation paths which could lead, under the conditions observed in Titan’s atmosphere, to the formation of (NCCN)− stable anions following the interaction with low-energy electrons.The present use of quantum, multichannel dynamics for the electron scattering part indicates that t...

We report here ((4)He)(N)-Rb(2)((3)Σ(u)) complexes, 2 ≤ N ≤ 20, analysed through a quantum diffusion Monte Carlo stochastic approach. The calculations show that the spin stretched dimer molecule is bound outside the pure He sub-complex, due to the stronger He-He potential as compared with the He-Rb(2) interaction, while the rare gas atom moiety pre...

A new full-dimension potential energy surface of the three-body He-Rb₂(³Σ(u)(+)) complex and a quantum study of small (⁴He)(N)-Rb₂(³Σ(u)(+)) clusters, 1 ≤ N ≤ 4, are presented. We have accurately fitted the ab initio points of the interaction to an analytical form and addressed the dopant's vibration, which is found to be negligible. A Variational...

The quantum dynamics of low-energy free electrons colliding with linear carbonaceous species like HC3N and HC5 N is examined to identify the locations and structural features of their metastable negative ions (resonant compound states of the colliding partners) with the aim of suggesting, at the molecular level, the possible mechanisms of anionic s...