Filters








3,432 Hits in 3.4 sec

Parallelization of a relativistic DFT code

Leonardo Belpassi, Loriano Storchi, Francesco Tarantelli, Antonio Sgamellotti, Harry M. Quiney
2004 Future generations computer systems  
We describe the implementation of some parallelization schemes for a relativistic four-component Dirac-Kohn-Sham program (BERTHA).  ...  Both schemes yield excellent performance results in terms of speed-up and scalability. The results obtained widen considerably the range of applicability of the method.  ...  These results substantially widen the applicability of the code to larger molecular systems and give strong support to the work for further developments of the relativistic four-component DFT.  ... 
doi:10.1016/j.future.2003.11.016 fatcat:bswdkl6fprhgzkfwv4hyavepae

UTChem — A Program for ab initio Quantum Chemistry [chapter]

Takeshi Yanai, Haruyuki Nakano, Takahito Nakajima, Takao Tsuneda, So Hirata, Yukio Kawashima, Yoshihide Nakao, Muneaki Kamiya, Hideo Sekino, Kimihiko Hirao
2003 Lecture Notes in Computer Science  
UTChem is a quantum chemistry software developed by Hirao's group at the University of Tokyo.  ...  UTChem is a research product of our work to develop new and better theoretical methods in quantum chemistry.  ...  , and Sports of Japan, and by a grant from the Genesis Research Institute.  ... 
doi:10.1007/3-540-44864-0_9 fatcat:ajdvxefkvfbrvjy2kzyggseyd4

Modern Software for Computer Modeling in Quantum Chemistry and Molecular Dynamics

Marina V. Malyshkina, Alexander S. Novikov
2021 Compounds  
The most popular modern programs for quantum chemical and molecular dynamics (classical, ab initio, and QM/MM) calculations, which are relevant for the investigation of nature and various properties of  ...  JDFTx [26] is a code, developed for plane-wave density-functional theory (DFT), and specifically the code that supports of all the standard functionalities presented in electronic DFT software and several  ...  Relativistic effects either are considered in scalar-relativistic or in full four-component formalism. A level comparable to the advanced level of numerical precision was achieved.  ... 
doi:10.3390/compounds1030012 fatcat:v2ibexq4gfgivf5oe6kf5bzdza

BAGEL: Brilliantly Advanced General Electronic-structure Library

Toru Shiozaki
2017 Wiley Interdisciplinary Reviews. Computational Molecular Science  
All of the programs are efficiently parallelized using both threads and MPI processes. We also discuss the code generator SMITH3, which has been used to implement some of the programs in BAGEL.  ...  The unique features include analytical CASPT2 nuclear energy gradients and derivative couplings, relativistic multireference wave functions based on the Dirac equation, and implementations of novel electronic  ...  The pilot KS-DFT code is also implemented using Libxc, 6 but it is neither efficient nor of production quality; we are hereby soliciting future collaboration for improving the DFT code.  ... 
doi:10.1002/wcms.1331 fatcat:5qiljeitcrbbvldm6x3lvo5ruy

The DIRAC code for relativistic molecular calculations

Trond Saue, Radovan Bast, André Severo Pereira Gomes, Hans Jørgen Aa. Jensen, Lucas Visscher, Ignacio Agustín Aucar, Roberto Di Remigio, Kenneth G. Dyall, Ephraim Eliav, Elke Fasshauer, Timo Fleig, Loïc Halbert (+15 others)
2020 Journal of Chemical Physics  
DIRAC is a freely distributed general-purpose program system for one-, two-, and four-component relativistic molecular calculations at the level of Hartree-Fock, Kohn-Sham (including range-separated theory  ...  DIRAC features a very general module for the calculation of molecular properties that to a large extent may be defined by the user and further analyzed through a powerful visualization module.  ...  CONCLUSIONS DIRAC is one of the earliest codes for four-component relativistic molecular calculations and the very first to feature eXact 2-Component (X2C) relativistic calculations. 26 A strength of  ... 
doi:10.1063/5.0004844 pmid:32486677 fatcat:vhbybqghincw3mfzju3xcsk5zq

Implementation of Relativistic Coupled Cluster Theory for Massively Parallel GPU-Accelerated Computing Architectures

Johann V. Pototschnig, Anastasios Papadopoulos, Dmitry I. Lyakh, Michal Repisky, Loïc Halbert, André Severo Pereira Gomes, Hans Jørgen Aa Jensen, Lucas Visscher
2021 Journal of Chemical Theory and Computation  
We therefore also briefly discuss an improvement of the parallel computing aspects of the relativistic self-consistent field algorithm of the DIRAC program.  ...  The code is designed for parallel execution on many compute nodes with optional GPU coprocessing, accomplished via the new ExaTENSOR back end.  ...  M.R. acknowledges the funding support from the Research Council of Norway through a Center of Excellence Grant (Grant no. 262695).  ... 
doi:10.1021/acs.jctc.1c00260 pmid:34370471 pmcid:PMC8444343 fatcat:mayywerphfb7rhczg5kfn3cs34

Recent developments in the PySCF program package [article]

Qiming Sun, Xing Zhang, Samragni Banerjee, Peng Bao, Marc Barbry, Nick S. Blunt, Nikolay A. Bogdanov, George H. Booth, Jia Chen, Zhi-Hao Cui, Janus Juul Eriksen, Yang Gao (+34 others)
2020 arXiv   pre-print
PYSCF is a Python-based general-purpose electronic structure platform that both supports first-principles simulations of molecules and solids, as well as accelerates the development of new methodology  ...  With several case studies, we show how users can easily implement their own methods using PYSCF as a development environment.  ...  RKS ( mol ) . run ( xc = ' b3lyp ') J , K = mf . get_jk ( mol , mf . make_rdm1 () ) FIG. 14: Code snippet showing the similarity between serial and MPI-parallel DFT calculations.  ... 
arXiv:2002.12531v1 fatcat:gkup57qilnc5xkbeidcunhvdja

Frozen-Density Embedding for including environmental effects in the Dirac-Kohn-Sham theory: an implementation based on density fitting and prototyping techniques [article]

Matteo De Santis, Diego Sorbelli, Valerie Vallet, Andre' Severo Pereira Gomes, Loriano Storchi, Leonardo Belpassi
2022 arXiv   pre-print
Finally, we applied the code to a series of Heavy (Rn) and Super-Heavy elements (Cn, Fl, Og) embedded in a C_60 cage to explore the confinement effect induced by C_60 on their electronic structure.  ...  This implementation has been enormously facilitated by BERTHA's python API (PyBERTHA), which provides a flexible framework of development by using all Python advantages in terms of code re-usability, portability  ...  which are based on the use of PyADF 30, 68 and of the PyEmbed module. 69, 105 is poses us in an ideal framework of having a reference non relativistic DFT-in-DFT FDE implementation where we can have  ... 
arXiv:2205.05523v1 fatcat:sbakslmjenakbijqkpimssrt6y

Recent developments in the PySCF program package

Qiming Sun, Xing Zhang, Samragni Banerjee, Peng Bao, Marc Barbry, Nick S. Blunt, Nikolay A. Bogdanov, George H. Booth, Jia Chen, Zhi-Hao Cui, Janus J. Eriksen, Yang Gao (+37 others)
2020 Journal of Chemical Physics  
PySCF is a Python-based general-purpose electronic structure platform that supports first-principles simulations of molecules and solids as well as accelerates the development of new methodology and complex  ...  With several case studies, we show how users can easily implement their own methods using PySCF as a development environment.  ...  FIG. 14 .FIG. 15 . 1415 FIG. 14.Code snippet showing the similarity between serial and MPI-parallel DFT calculations. TABLE I . I Major features of PYSCF as of version 1.7.1.  ... 
doi:10.1063/5.0006074 pmid:32668948 fatcat:f4uw7mexonbbznzkgv6d4dh53e

GGA/PBE study of the spin isomers of Fe34,40, Co23,34, and Co12Cu Clusters with Selected Geometries

Faustino Aguilera-Granja, Andrés Vega, Luis Carlos Balbás
2017 Journal of the Mexican Chemical Society  
We have calculated within the same tools the magnetic isomers of Co<sub>12</sub>Cu cluster aimed to re-visit a former DFT prediction of an anti-ferromagnetic ground state.  ...  Our results exemplify the difficulties of the current DFT approaches to describe the magnetic properties of transition metal systems.  ...  F.A-G acknowledges a grant of University of Valladolid, where part of this work was performed.  ... 
doi:10.29356/jmcs.v56i3.298 fatcat:hezx2y6ewvcdnlf35keyf2hhke

Nuclear magnetic resonance shielding constants and chemical shifts in linear 199Hg compounds: A comparison of three relativistic computational methods

Vaida Arcisauskaite, Juan I. Melo, Lars Hemmingsen, Stephan P. A. Sauer
2011 Journal of Chemical Physics  
Density functional calculations of nuclear magnetic shieldings using the zeroth-order regular approximation (ZORA) for relativistic effects: ZORA nuclear magnetic resonance A fully relativistic method  ...  for calculation of nuclear magnetic shielding tensors with a restricted magnetically balanced basis in the framework of the matrix Dirac-Kohn-Sham equation We investigate the importance of relativistic  ...  LR-ESC calculations LR-ESC calculations were carried out using the DALTON V2.0 code 37 at HF and DFT/BP86 levels with the exception of the σ (DIA-K) contributions, 60 which are implemented in a local  ... 
doi:10.1063/1.3608153 pmid:21806118 fatcat:4mker7u4nnbmblviutwt642aly

Absolute NMR shielding scales in methyl halides obtained from experimental and calculated nuclear spin-rotation constants

Daniel F. E. Bajac, I. Agustín Aucar, Gustavo A. Aucar
2021 Physical Review A  
The non-relativistic "Ramsey-Flygare relationship" is the most used procedure to obtain semiexperimental NMR absolute shieldings by a correspondence between NMR shieldings (σ) and nuclear spin-rotation  ...  The best fit between calculations of M and experimental data are obtained from calculations at 4c-PBE0 level of theory in all cases, but not for M ,Cl which suggest that a revision of the available experimental  ...  We thank the Institute for Modeling and Innovation on Technologies (IMIT) of the National Scientific and Technical Research Council and the Northeastern University of Argentina for their support and for  ... 
doi:10.1103/physreva.104.012805 fatcat:lvggohpqtfcaxkyasp2hjk6gwi

Electronic structure ofLaNiO3−xthin films studied by x-ray photoelectron spectroscopy and density functional theory

Š. Masys, S. Mickevičius, S. Grebinskij, V. Jonauskas
2010 Physical Review B  
The significance of spin-orbit coupling to the electronic structure of LaNiO 3 is revealed by relativistic molecular HF study allowing to theoretically identify the doublet splitting of La 5p.  ...  We present the experimental and theoretical study of x-ray photoelectron spectroscopy spectrum of LaNiO 3−x thin films deposited onto a ͑100͒-plane oriented NdGaO 3 substrate by applying a reactive dc  ...  The photoelectrons were measured using a hemispherical analyzer with parallel detection capability ͑SCIENTA SES-200͒.  ... 
doi:10.1103/physrevb.82.165120 fatcat:3rvpn33gnvahdef27luflob7ka

Influence of the nuclear charge distribution and electron correlation effects on magnetic shieldings and spin-rotation tensors of linear molecules

I. Agustín Aucar, Carlos A. Giménez, Gustavo A. Aucar
2018 RSC Advances  
The analysis is performed on the relativistic and non relativistic regimes.  ...  The origin and the size of both, electron correlation and nuclear charge distribution on shieldings and spin-rotations of heavy-atom containing linear molecules are shown.  ...  on M t,At is 5% of its total correlated value at relativistic DFT/PBE0 level of theory.  ... 
doi:10.1039/c8ra03948h pmid:35541654 pmcid:PMC9080724 fatcat:bpx2gndczfgrbga55pdbxwzzsi

Recent advances and perspectives in four-component Dirac–Kohn–Sham calculations

Leonardo Belpassi, Loriano Storchi, Harry M. Quiney, Francesco Tarantelli
2011 Physical Chemistry, Chemical Physics - PCCP  
We describe our implementation of an all-electron DKS approach based on the use of G-spinor basis sets, Hermite Gaussian functions, state-of-the-art density-fitting techniques and memory distributed parallelism  ...  We review recent theoretical and computational advances in the full relativistic four-component Dirac-Kohn-Sham (DKS) approach and its application to the calculation of the electronic structure of chemical  ...  ) and project HP10BO0PYX (AuCat) of the Italian SuperComputer Resource Allocation (ISCRA-CINECA).  ... 
doi:10.1039/c1cp20569b pmid:21670843 fatcat:o55zunbhyzgsdmn37cm3jibioa
« Previous Showing results 1 — 15 out of 3,432 results