Download Electronic Structure Theory

Electronic Structure Theory
The last few years
Research Fields
Many-body Physics of Electrons
O. Cramariuc: PhD Thesis (2006)
§ Quantum dynamics of light–matter interaction
§ Development of Quantum Monte Carlo approach
§ Development of Density Functional Theory
§ Finite temperature quantum statistics
H-P. Komsa: PhD Thesis (2008)
Materials Physics and Chemistry
§ Compound semiconductors: bulk defects,
surfaces, interfaces, nanostructures
§ Organic materials, photoabsorption, electron
transfer, nanostructures
§ Finite temperature Quantum Chemistry
SiO2
M. Leino: PhD Thesis (2007)
I. Kylänpää: PhD Thesis (2011)
M. Mäki-Jaskari: PhD Thesis (2004)
M. Viitala: PhD Thesis (2012)
The Present and The Challenges
Electronic structure is the basic
concept behind structure and
properties of matter!
Ground State and
Excited States
Eigenvalue Problem
Quantum Statistics
§ At zero-Kelvin
§ Feynman path-integral approach
§ Hartree–Fock, CI, MCHF
§ Density Functional
Theory(DFT – ”the work
horse”)
Explicit Time Propagation
§ At zero-Kelvin
§ Time-Dependent DFT (TDDFT)
Robust Solution to the Semiconductor
BAND GAP PROBLEM
§ Evaluation of the
missing discontinuity:
Total (solid curve),
LDA–KS (square) and
GGA-KS
(circle)compared with
the experimental (star).
§ Further work ongoing
www.tut.fi/semiphys
Temperature or Time
Dependent States
Applications with DFT
Surface physics and chemistry
§ Adsorption of small and aromatic molecules
§ Adsorbate (quantum) dynamics
§ Van der Waals interaction
§ Magnetic defects
Compound semiconductor physics
§ Surface and interface electronic structure:
bands and charge carriers
§ X-STM image simulation
§ Defect structure and (formation) energies
§ Optical properties (light–matter interaction)
ω
Path Integral Monte Carlo (PIMC)
§ Explicitly temperature dependent
NVT-ensemble simulation
§ Full account of electronic correlations
§ Allows model and calculations beyond
Born–Oppenheimer approximation,
i.e., potential energy surface (PES)
§ Accepting the challenge of
FERMION SIGN PROBLEM !
T>0 Ab Initio Quantum Chemistry
Small molecules and atoms
H2+H+
H2++H, so far
§ H2+, He, H–, H2, Ps2, H3+
§ Finite temperature included
§ Exact correlation, nodal surfaces for exchange
Continuous/periodic systems
§ Two-component Fermi sea: e– p+, e– e+
§ LDA type correlation functional for the above
Ab initio chemical reactions
§ Dissociation–recombination in thermal equilibr.
§ Model for on or beyond BO-PES
§ Work for time dependence in progress
§ Fundamental issues in classical to quantum
transition: decoherence