0000000000001545
AUTHOR
Gian Luigi Bendazzoli
showing 7 related works from this author
Full Configuration-Interaction Study on the Tetrahedral Li4 Cluster
2008
International audience; The Li4 cluster low lying electronic states were studied. In particular we investigated the tetrahedral geometry at full CI and coupled cluster level, with basis sets of increasing quality. The 5A2 electronic state, characterized by having all the valence electrons unpaired, forming a quite stable no-pair bonding state, was studied in greater detail. In order to compare the energies we also studied the Li4 rhombus singlet ground state. The ability of coupled cluster with perturbative triples to correctly reproduce energy levels in a quasi-degenerate system was validated with respect to the full CI.
Computing the position-spread tensor in the CAS-SCF formalism II: Spin partition
2016
Abstract The Spin-Partitioned (SP) Total Position-Spread (TPS) tensor provides finer insights that supplement the information conveyed in the Spin-Summed (SS) TPS. The calculation of the SP-TPS has been implemented in the MOLPRO code for CAS-SCF wavefunctions allowing the study of electron (de) localization in relatively large molecular systems where the FCI treatment is rather unfeasible. An illustrative example considering one-dimensional Be wires is given as an application of the formalism.
Full configuration interaction calculation of Be3.
2004
The full configuration interaction (FCI) study of the ground state of the neutral beryllium trimer has been performed using an atomic natural orbitals [3s2p1d] basis set. Both triangular and linear structures have been considered for the Be(3) cluster. The optimal geometry for the equilateral triangle has been calculated. The potential energy cut sections along the normal a(1)(') mode and one of the components of the e(') mode have then been studied. The FCI symmetric atomization potential of the linear cluster is also reported. It shows a secondary van der Waals minimum at a long bond distance. All singular points in the potential energy curves are characterized. Other properties, like dis…
Code Interoperability and Standard Data Formats in Quantum Chemistry and Quantum Dynamics: The Q5/Q5cost Data Model
2014
Code interoperability and the search for domain-specific standard data formats represent critical issues in many areas of computational science. The advent of novel computing infrastructures such as computational grids and clouds make these issues even more urgent. The design and implementation of a common data format for quantum chemistry (QC) and quantum dynamics (QD) computer programs is discussed with reference to the research performed in the course of two Collaboration in Science and Technology Actions. The specific data models adopted, Q5Cost and D5Cost, are shown to work for a number of interoperating codes, regardless of the type and amount of information (small or large datasets) …
High-spin states in tetrahedral X4 clusters (X = H, Li, Na, K)
2010
The high-spin electronic states for lithium, sodium, and potassium four-atom clusters were studied. In particular, we performed coupled cluster geometry optimization of the quintet state in tetrahedral geometry. The quintet state of these systems is characterized by having all the valence electron Unpaired, giving rise to the so-called no-pair bonding. Single-point full configuration interaction computations on the equilibrium geometries for the various Clusters are also presented. The analysis of the valence orbitals in a localized representation confirms the importance of the p atomic orbitals to explain this unusual type of bond. (C) 2009 Wiley Periodicals, Inc. Int J Quantum Chem 110: 8…
The problem of interoperability: A common data format for quantum chemistry codes
2007
A common format for quantum chemistry (QC), enhancing code interoperability and communication between different programs, has been designed and implemented. An XML-based format, QC-ML, is presented for representing quantities such as geometry, basis set, and so on, while an HDF5-based format is presented for the storage of large binary data files. Some preliminary applications that use the format have been implemented and are also described. This activity was carried out within the COST in Chemistry D23 project “MetaChem,” in the Working Group “A meta-laboratory for code integration in ab initio methods.” © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Full configuration interaction calculation of singlet excited states of Be3
2004
The full configuration interaction (FCI) study of the singlets vertical spectrum of the neutral beryllium trimer has been performed using atomic natural orbitals [3s2p1d] basis set. The FCI triangular equilibrium structure of the ground state has been used to calculate the FCI vertical excitation energies up to 4.8 eV. The FCI vertical ionization potential for the same geometry and basis set amounts to 7.6292 eV. The FCI dipole and quadrupole transition moments from the ground state are reported as well. The FCI electric quadrupole moment of the X (3)A(1) (') ground state has been also calculated with the same basis set (Theta(zz)=-2.6461 a.u., Theta(xx)=Theta(yy)=-1/2Theta(zz)). Twelve of …