2018-10-19 01:06:18 +02:00
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Introduction
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============
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What it is
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""""""""""
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The |qp| is an open-source programming environment for quantum chemistry,
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especially for `wave function methods <https://en.wikipedia.org/wiki/Ab_initio_quantum_chemistry_methods>`_.
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The main goal is the development of selected configuration interaction (sCI)
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methods and multi-reference perturbation theory (MR-PT) in the
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determinant-driven paradigm. The determinant-driven framework allows the
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programmer to include any arbitrary set of determinants in the variational
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space, and thus gives a complete freedom in the methodological development. All
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the programs are developed with the `IRPF90`_ code generator, which simplifies
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the development of new programs.
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What it is not
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The |qp| is *not* a general purpose quantum chemistry program.
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First of all, it is a library. The users of the |qp| should develop
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their own programs.
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The |qp| has been designed specifically for sCI, so all the
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algorithms which are programmed are not adapted to run SCF or DFT calculations
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2018-10-19 11:32:58 +02:00
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on thousands of atoms. Currently, the systems targeted have less than 500
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molecular orbitals.
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2018-10-19 01:06:18 +02:00
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The |qp| is *not* a massive production code. For conventional
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2018-10-19 11:32:58 +02:00
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methods such as Hartree-Fock, CISD or MP2, the users are recommended to use the
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2018-10-19 01:06:18 +02:00
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existing standard production codes which are designed to make these methods run
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fast. Again, the role of the |qp| is to make life simple for the
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developer. Once a new method is developed and tested, the developer is encouraged
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to consider re-expressing it with an integral-driven formulation, and to
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2018-10-19 11:32:58 +02:00
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implement the new method in open-source production codes, such as `NWChem`_
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2018-10-19 01:06:18 +02:00
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or `GAMESS`_.
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Applications
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Multiple programs were developed with the |qp|, such as:
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- Selected Full-CI + Epstein-Nesbet PT2 (CIPSI)
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- Hybrid stochastic/deterministic MR-PT2
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- CIS, CISD, MP2
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- Selected CISD
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- Jeziorsky-Monkhorst MR-PT2
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- Selected CAS+SD
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- Selected difference-dedicated CI (DD-CI)
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- Multi-Reference Coupled Cluster (MR-CCSD)
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- CIPSI with range-separated DFT
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All these programs can generate ground and excited states, and spin pure wave functions
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(eigenstates of S²).
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.. Links ..
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.. _IRPF90: http://irpf90.ups-tlse.fr
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.. _NWChem: http://www.nwchem-sw.org/
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.. _GAMESS: https://www.msg.chem.iastate.edu/gamess/
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.. |qp| replace:: Quantum Package
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