9 research outputs found
Siesta: Recent developments and applications
A review of the present status, recent enhancements, and applicability of the SIESTA program is presented. Since its debut in the mid-1990s,
SIESTA’s flexibility, efficiency, and free distribution have given advanced materials simulation capabilities to many groups worldwide. The core
methodological scheme of SIESTA combines finite-support pseudo-atomic orbitals as basis sets, norm-conserving pseudopotentials, and a realspace grid for the representation of charge density and potentials and the computation of their associated matrix elements. Here, we describe
the more recent implementations on top of that core scheme, which include full spin–orbit interaction, non-repeated and multiple-contact
ballistic electron transport, density functional theory (DFT)+U and hybrid functionals, time-dependent DFT, novel reduced-scaling solvers,
density-functional perturbation theory, efficient van der Waals non-local density functionals, and enhanced molecular-dynamics options. In
addition, a substantial effort has been made in enhancing interoperability and interfacing with other codes and utilities, such as WANNIER90 and
the second-principles modeling it can be used for, an AiiDA plugin for workflow automatization, interface to Lua for steering SIESTA runs, and
various post-processing utilities. SIESTA has also been engaged in the Electronic Structure Library effort from its inception, which has allowed
the sharing of various low-level libraries, as well as data standards and support for them, particularly the PSeudopotential Markup Language
definition and library for transferable pseudopotentials, and the interface to the ELectronic Structure Infrastructure library of solvers. Code
sharing is made easier by the new open-source licensing model of the program. This review also presents examples of application of the
capabilities of the code, as well as a view of on-going and future developments.
Published under license by AIP Publishing.Siesta development was historically supported by different Spanish National Plan projects (Project Nos. MEC-DGES-PB95-0202, MCyT-BFM2000-1312, MEC-BFM2003-03372, FIS2006-12117, FIS2009-12721, FIS2012-37549, FIS2015-64886-P, and RTC-2016-5681-7), the latter one together with Simune Atomistics Ltd. We are thankful for financial support from the Spanish Ministry of Science, Innovation and Universities through Grant No. PGC2018-096955-B.
We acknowledge the Severo Ochoa Center of Excellence Program [Grant Nos. SEV-2015-0496 (ICMAB) and SEV-2017-0706 (ICN2)], the GenCat (Grant No. 2017SGR1506), and the European Union MaX Center of Excellence (EU-H2020 Grant No. 824143).
P.G.-F. acknowledges support from Ramón y Cajal (Grant No. RyC-2013-12515). J.I.C. acknowledges Grant No. RTI2018-097895-B-C41.
R.C. acknowledges the European Union’s Horizon 2020 Research and Innovation Program under Marie Skłodoswka-Curie Grant Agreement No. 665919.
D.S.P, P.K., and P.B. acknowledge Grant No. MAT2016-78293-C6, FET-Open No. 863098, and UPV-EHU Grant No. IT1246-19.
V. W. Yu was supported by a MolSSI Fellowship (U.S. NSF Award No. 1547580), and V.B. and V.W.Y. were supported by the ELSI Development by the NSF (Award No. 1450280). We also acknowledge Honghui Shang and Xinming Qin for giving us access to the honpas code, where a preliminary version of the hybrid functional support described here was implemented.
We are indebted to other contributors to the Siesta project whose names can be seen in the Docs/Contributors.txt file of the Siesta distribution, and we thank those, too many to list, contributing fixes, comments, clarifications, and documentation for the code.Peer reviewe
The tautomeric structures of 3(5),3′(5′)-azopyrazole [(E)-1,2-di(1H-pyrazol-3(5)-yl)diazene)]: The combined use of NMR and electronic spectroscopies with DFT calculations
An azo derivative of 1H-pyrazole has been chosen to study the information obtained from different techniques for determining the structure of a non-crystalline compound in the solid-state and in solution. Syn–anti isomerism of the azo group, prototropic tautomerism of the 1H-pyrazole and rotation about the pyrazole–azo group resulted in 20 structures that were analyzed. Energy calculations, 13C and 15N chemical shifts, 1H–1H coupling constants and electronic spectra reduced the 20 possible structures to only one, the 3,3′-Z,Z-anti-azopyrazole
The tautomeric structures of 3(5),3′(5′)-azopyrazole [(E)-1,2-di(1H-pyrazol-3(5)-yl)diazene)]: The combined use of NMR and electronic spectroscopies with DFT calculations
An azo derivative of 1H-pyrazole has been chosen to study the information obtained from different techniques for determining the structure of a non-crystalline compound in the solid-state and in solution. Syn-anti isomerism of the azo group, prototropic tautomerism of the 1H-pyrazole and rotation about the pyrazole-azo group resulted in 20 structures that were analyzed. Energy calculations, 13C and 15N chemical shifts, 1H- 1H coupling constants and electronic spectra reduced the 20 possible structures to only one, the 3,3′-Z,Z-anti-azopyrazole. © 2012 Elsevier B.V. All rights reserved.Peer Reviewe