Quantum Calculations. B. Barbiellini email@example.com Thematics seminar April 21,2005. Goal: Solve the SchrÃ¶dinger equation . Application: Description of chemical bonds. Outline. Independent Particle Approximation (IPM) and Hartree Fock (HF) SCF: Basis sets.
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B. Barbiellini firstname.lastname@example.org
Application: Description of chemical bonds
Ab-initio - from the origins (First-principles)
No experimental parameters
Few physical constants c, h, me, qe
min<| H|> = E
Correlation energy: energy contributions beyond SCF
Hartree-Fock (HF) SCF
a is spin up
F j =e j F is an effective one-particle hamiltonian which depend on MO’s Self Consistent Field (SCF).
Basis set – mathematical representation of molecular orbitals
H(1s) C(1s,2s,2p) → CH4:
9 basis functions
} route section
molecular structure section
atomic symbols (or numbers)
xyz coordinates (or z-matrix)
#RHF/6-31G(d) Pop=Full Test
RHF/6-31G(d) formaldehyde single point
C 0.0 0.0 0.0
O 0.0 1.22 0.0
H 0.94 -0.54 0.0
H -0.94 -0.54 0.0
} title section
Isaacs et al., PRL 82 (1999) 600
Wavelike fringes corresponding to interference between the electrons on neighboring sigma and hydrogen bonding sites
Quantum calculations are of interest because they can deal with electronic effects, electron de-localization, charge-transfer, and other phenomena, which are otherwise difficult or impossible to treat at the level of classical mechanics.