Andreas Markmann

I am using the Heidelberg MCTDH package in my research.

You can download my PhD thesis (10.5 MB, two A5 pages on each landscape page).
Joint winner of Carey-Foster Prize for Postgraduate Research in 2005 for thesis.

9th Nov 2005: "Adiabatic and Diabatic Representations" by Andreas Markmann. Download notes / talk.
21st Nov 2005: "The multi-mode vibronic-coupling approach" by Sabyashachi Mishra. Download talk.

Allene and Pentatetraene Cations: Poster at Faraday Discussion 127 and the
6th International Symposium of the Volkswagen-Stiftung on Intra- and Intermolecular Electron Transfer
DFT of HCl On MgO: Poster used at DFT 2001 conference at the Royal Institution of Great Britain
Visualisation of a phonon mode which is localised at a step

Molecule viewer

Theoretical Study of Photoinduced Reactions in Ionic Crystals; Mechanisms, Energy Dissipation and Coherence Effects
1. Introduction, 2. Methods of Classical Dynamics and Data Analysis, 3. Localisation of Vibrational Modes at Ionic Crystal Surfaces, 4. DFT Calculations of HCl Adsorbed on the MgO(001) Surface, 5. Shell Model Dynamics of HCl on the MgO(001) Surface Terrace, 6. Quantum Control of HCl on MgO(001), 7. Quantum Control of the STE Separation in Alkali Halides

Download: 02-AMarkmann2004-PhD.pdf

Allene and pentatetraene cations as models for intramolecular charge transfer: Vibronic coupling Hamiltonian and conical intersections
Vibronic coupling effects involving cationic charge localized states. Parameters for a five-state, all-mode diabatic vibronic coupling model Hamiltonian were least-square fitted to ab initio potentials.
Download: 03-AMarkmann2005-1.pdf

Simulation of a complex spectrum: Interplay of five electronic states and 21 vibrational degrees of freedom in C₅H₄⁺
Photoelectron spectrum of the pentatetraene cation in the neighborhood of the state with charge-localized components. Quantum nuclear dynamics calculations using the multiconfiguration time-dependent Hartree method, taking all 21 vibrational normal modes into account. Compared to experiment, the main features are reproduced.
Download: 04-AMarkmann2005-2.pdf

Simulation of coherent control of hydroxyl formed due to HCl adsorption on MgO(001)
The optimal control technique is used to design laser fields that maximise the yield of hydroxyl molecules at the MgO(001) surface in a vibrationally highly excited state. The main frequencies and chirp parameters of the predicted fields are extracted. Predicted pulses involve considerable contributions from double excitations. Taking dissipation into account, a lowering of the excitation yield is predicted but only by 50%, so that the proposed process remains effective. A radiative mechanism is proposed to desorb hydrogen from the vibrationally excited state of OH^-.
Download: 05-AMarkmann2006-1.pdf

Chemisorption of HCl to the MgO(001) surface: A DFT study
We find dissociative chemisorption at a coverage smaller than 0.5 monolayer with a Cl^- ion electrostatically coupled to the OH^- ion at the surface oxygen site. At rising coverage, an increase in dipole-dipole repulsion between HCl molecules leads to a lowering of the adsorption energy per HCl and a change of binding towards hydrogen-bridge type as well as a lowering of the activation energy for Cl^- diffusion.
Download: 06-AMarkmann2006-2.pdf

Photoinduced Electron and Proton Transfer in the Hydrogen-Bonded Pyridine-Pyrrole System
We present a detailed analysis of the mechanism of photoinduced electron and proton transfer in the planar pyrrole-pyridine hydrogen-bonded system, a model for the photochemistry of hydrogen bonds in DNA base pairs. Two different crossings, an avoided crossing and a conical intersection, are the key steps for forward and backward electron and proton transfer providing to the system photostability against UV radiation by restoring the system in its initial electronic and geometric structure.
Download: 07-AMarkmann2007-1.pdf

Adaptive Control of Coherent Electron Transport in Semiconductors
The feasibility of using shaped electrostatic potentials is explored for achieving specified final scattering distributions of an electron wave packet in two dimensional GaAs/AlGaAs heterostructures. Simulations suggest that highly complex target scattering objectives may be achieved by employing adaptive closed loop optimal control to determine the voltages of multi-pixel surface gates. A proposed experimental design is described for testing the Adaptive Control of Coherent ElectroN Transport in Semiconductors (ACCENTS).
Download: 16-AMarkmannPre-6.pdf

Theoretical Study of Intramolecular Charge Transfer in the Allene and Pentatetraene Cations
We have simulated charge transfer processes in the allene and pentatetraene cations using quantum nuclear dynamics calculations, taking five electronic states and vibrational normal modes into account (15 and 21, respectively). These ultrafast processes depend crucially on the vibronic interaction between the electronic states of interest through a conical intersection. The transition rate can be influenced by displacing the initial wave packet along vibrational modes with non-negligible Poisson parameters, corresponding to non-Condon ionisation.
Download: 15-AMarkmannPre-5.pdf

Simulation of Coherent Dissociation of the Self-Trapped Exciton in Alkali Halides
We have used existing theoretical and experimental results to parameterise a generic model potential for the self-trapped exciton in alkali halides and performed nuclear quantum dynamics simulations using grid-based wave function propagation techniques. A photoinduced reaction is proposed that separates the self-trapped exciton into a pair of point defects via an electronic excitation. A double-pump, double-dump pulse scheme is proposed to attain a satisfactory yield of separated defect pairs.
Download: 14-AMarkmannPre-4.pdf<

Shell Model Dynamics of HCl on the MgO(001) Surface Terrace
HCl adsorbed on the MgO(001) surface is studied with shell model lattice dynamics and molecular dynamics. The stretch mode frequency of the OH^- molecule formed due to HCl adsorption is well separated from the MgO slab spectrum while its rotational and librational modes are closer but still separated. No internal HCl modes exist, confirming the notion of dissociated adsorption of HCl. After equilibrium molecular dynamics (MD), a sudden excitation of the OH^- stretch mode is applied to a snapshot of the equilibrium dynamics. In the ensuing MD, energy exchange between the OH^- stretch mode and the surface proceeds exclusively via the OH^- rotational and librational modes, whose orientations at each time step are readily derived from symmetry considerations. A model is extracted for the dissipation of the OH^- stretch energy.
Download: 13-AMarkmannPre-3.pdf

Lattice Dynamics Simulation of Ionic Crystal Surfaces: II. Vibrational Modes Localised at Surface Steps and Corners
Attenuation parameter functions are used to quantify the degree of localisation of normal modes at steps in the KBr(001), MgO(001) and CaF2(111) surfaces and at corners in a finite cube of MgO as examples for one- and zero-dimensional defects in a surface. By the frequencies of the localised modes thus obtained it can then be decided whether an adsorbed molecule is likely to couple to the surface. Out of the materials studied, step-localised modes are predicted only in MgO and KBr. The maximum degree of localisation is weaker in MgO, as it has no pronounced phonon band gap. Step modes with motion along and around the step are predicted. Based on these findings, mechanisms for vibrational energy transport along step funnelled by step localised modes are proposed. Normal modes localised at the corners of an MgO cube are identified with an analogous criterion. They correspond to similar vibrational modes at kinks in surface steps, whose properties are extrapolated.
Download: 12-AMarkmannPre-2.pdf

Lattice Dynamics Simulation of Ionic Crystal Surfaces: I. Criteria for Vibrational Mode Localisation and Surface Modes
A simple function, called attenuation parameter, is presented that can be used to extract quantitative information on the degree of localisation of normal modes at locations of arbitrary dimensionality from eigenvector components calculated in lattice dynamics simulations. As examples for localisation at two-dimensional locations, modes localised at the KBr(001), MgO(001) and CaF2(111) surfaces modelled by periodic shell model slabs are determined using the attenuation parameter for surface localisation. This allows to gain an overview of the frequencies of the crystalline vibrations localised at the surface which is important for the vibrational interaction with adsorbed molecules.
Download: 11-AMarkmannPre-1.pdf