Programs in Physics & Physical Chemistry
|[Licence| Download | New Version Template] aese_v2_0.tar.gz(2961 Kbytes)|
|Manuscript Title: CheMPS2: improved DMRG-SCF routine and correlation functions|
|Authors: Sebastian Wouters, Ward Poelmans, Stijn De Baerdemacker, Paul W. Ayers, Dimitri Van Neck|
|Program title: CheMPS2|
|Catalogue identifier: AESE_v2_0|
Distribution format: tar.gz
|Journal reference: Comput. Phys. Commun. 191(2015)235|
|Programming language: C++.|
|Operating system: Linux.|
|RAM: 10MB - 512GB|
|Keywords: SU(2) spin-adapted DMRG, ab initio quantum chemistry, DIIS, Edmiston-Ruedenberg orbital localization, Fiedler vector, two-orbital mutual information.|
|PACS: 31.15.ae, 31.15.vj, 31.50.Df.|
External routines: Basic Linear Algebra Subprograms (BLAS), Linear Algebra Package (LAPACK), GNU Scientific Library (GSL), Hierarchical Data Format Release 5 (HDF5), and Open Multi-Processing (OpenMP)
Does the new version supersede the previous version?: Yes
Nature of problem:
The many-body Hilbert space grows exponentially with the number of single-particle states. Exact diagonalization solvers can therefore only handle small active spaces, of up to 16 electrons in 16 orbitals. Interesting active spaces are often significantly larger.
The density matrix renormalization group allows to extend the size of active spaces, for which numerically exact solutions can be found, significantly. In addition, it provides a rigorous variational upper bound to energies, as it has an underlying wavefunction ansatz, the matrix product state.
Reasons for new version:
The DMRG routine is 20% faster in the new version. Several features were added to the augmented Hessian Newton-Raphson DMRG-SCF routine. In addition, five correlation functions were implemented to study the electronic structure in a comprehensible way. A python interface to the library is provided.
Summary of revisions:
Our implementation of the density matrix renormalization group is spin-adapted. This means that targeted eigen-states in the active space are exact eigenstates of the total electronic spin operator. Hamiltonians which break this symmetry cannot be handled by our code.
The nature of the matrix product state ansatz allows for exact spin coupling. In CheMPS2, the total electronic spin is imposed (not just the spin projection), in addition to the particle-number and abelian point-group symmetries.
A more elaborate overview of the new features can be found in the CASSCF, Correlations, DMRGSCFunitary and EdmistonRuedenberg class references in the doxygen documentation, either generated by the instructions in README.md or online . Updated versions of CheMPS2 will be provided at its public git repository .
Examples are given in Table 1. It should be mentioned that the running time depends strongly on the size of the targeted active space, the density of states, the orbital choice and ordering, and the reduced virtual dimension DSU(2).
|||S. Wouters, W. Poelmans, P. W. Ayers and D. Van Neck, CheMPS2: A free open-source spin-adapted implementation of the density matrix renormalization group for ab initio quantum chemistry, Computer Physics Communications 185 (6), 1501-1514 (2014). http://dx.doi.org/10.1016/j.cpc.2014.01.019|
|||T. Yanai, Y. Kurashige, D. Ghosh and G. K.-L. Chan, Accelerating convergence in iterative solution for large-scale complete active space self-consistent-field calculations, International Journal of Quantum Chemistry 109 (10), 2178-2190 (2009). http://dx.doi.org/10.1002/qua.22099|
|||C. Edmiston and K. Ruedenberg, Localized atomic and molecular orbitals, Reviews of Modern Physics 35 (3), 457-464 (1963). http://dx.doi.org/10.1103/RevModPhys.35.457|
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|||J. Rissler, R. M. Noack and S. R. White, Measuring orbital interaction using quantum information theory, Chemical Physics 323 (2-3), 519-531 (2006). http://dx.doi.org/10.1016/j.chemphys.2005.10.018|
|||G. Barcza, R. M. Noack, J. Solyom and O. Legeza, Entanglement patterns and generalized correlation functions in quantum many body systems (2014). http://arxiv.org/abs/1406.6643|
|||J. Hachmann, J. J. Dorando, M. Aviles and G. K.-L. Chan, The radical character of the acenes: A density matrix renormalization group study, Journal of Chemical Physics 127 (13), 134309 (2007). http://dx.doi.org/10.1063/1.2768362|
|||S. Wouters, CheMPS2 documentation, http://sebwouters.github.io/CheMPS2/index.html (2014).|
|||S. Wouters, CheMPS2: a spin-adapted implementation of DMRG for ab initio quantum chemistry, https://github.com/SebWouters/CheMPS2 (2014).|
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