EXP-T (software)
 | |
| Developer(s) | The EXP-T Development Team |
|---|---|
| Stable release | 1.5.0
|
| Written in | C99, Fortran 90 |
| Engine | |
| Operating system | Linux, macOS |
| Type | Computational chemistry |
| License | LGPL |
| Website | www |
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EXP-T.[1] is a relativistic ab initio quantum chemistry program package. EXP-T is designed for high-precision modeling of molecular electronic structure using the relativistic Fock space multireference coupled cluster method (FS-RCC). EXP-T is written from scratch mainly in the C99 programming language and is currently focused on Unix-like operating systems.
EXP-T is free software; the source code is available on GitHub.
Capabilities
Electronic structure models implemented in EXP-T[1]:
- single-point energy calculations with any point groups and (nearly) all Hamiltonians, implemented in DIRAC (4c-DC, X2Cmmf, 2c-ECP, non-relativistic);
- ground state energy calculations: CCSD, CCSD(T), CCSDT-n (n=1,2,3), CCSDT models;
- FS-MRCCSD method for excited states is implemented for the (0h1p), (1h0p), (1h1p), (0h2p), (2h0p) Fock space sectors;
- FS-MRCC models for excited states accounting for triples (CCSDT-n (n=1,2,3), CCSDT) are implemented for the (0h1p), (1h0p), (0h2p) Fock space sectors[2];
- "dynamic" energy denominators shifts[3] as a solution of the intruder-state problem;
- Padé extrapolation to the zero-shift limit[4];
- finite-field transition moments calculations[5];
- quasidiabatization of spin-orbit-coupled states and spin-orbit functions extraction[3]
To the moment, the EXP-T package doesn’t include subroutines for solving (Dirac-)Hartree-Fock equations and subsequent four-index transformation, so molecular integrals have to be imported from third-party electronic structure packages via interfaces. Currently, EXP-T is interfaced with the DIRAC program package, thus getting access to the wide variety of Hamiltonians and property operators implemented there.
Features for high-performance calculations include OpenMP parallelization (for shared-memory systems) and parallel calculations on Nvidia GPUs using the CUDA platform.
See also
References
- ↑ 1.0 1.1 Oleynichenko, A. V.; Zaitsevskii, A.; Eliav, E. (2020). "Towards High Performance Relativistic Electronic Structure Modelling: The EXP-T Program Package". arXiv:2004.03682 [physics.comp-ph].
- ↑ Oleynichenko, A. V.; Zaitsevskii, A.; Skripnikov, L. V.; Eliav, E. (2020). "Relativistic Fock-Space Coupled Cluster Method for Many-Electron Systems: Non-Perturbative Account for Connected Triple Excitations". Symmetry. 12 (7): 1101. doi:10.3390/sym12071101.
- ↑ 3.0 3.1 Zaitsevskii, A.; Mosyagin, N. S.; Stolyarov, A. V.; Eliav, E. (2017). "Approximate relativistic coupled-cluster calculations on heavy alkali-metal diatomics: Application to the spin-orbit-coupled A1Σ+ and b3Π states of RbCs and Cs2". Phys. Rev. A. 96 (2): 022516. Bibcode:2017PhRvA..96b2516Z. doi:10.1103/PhysRevA.96.022516.
- ↑ Zaitsevskii, A.; Eliav, E. (2018). "Padé extrapolated effective Hamiltonians in the Fock space relativistic coupled cluster method". Int. J. Quantum Chem. 118 (23): e25772. doi:10.1002/qua.25772.
- ↑ Zaitsevskii, A.; Skripnikov, L. V.; Kudrin, A. V.; Oleinichenko, A. V.; Eliav, E.; Stolyarov, A. V. (2018). "Electronic Transition Dipole Moments in Relativistic Coupled-Cluster Theory: the Finite-Field Method". Opt. Spectrosc. 124 (4): 451–456. Bibcode:2018OptSp.124..451Z. doi:10.1134/S0030400X18040215. Unknown parameter
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External links
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