Papers by Hans-dieter Meyer
Computing Eigenstates by Relaxation and Improved Relaxation
Multidimensional Quantum Dynamics, 2009
Surface Science Letters, 1984
The well-known classical path approximation is applied to a calculation of diffraction mtensittes... more The well-known classical path approximation is applied to a calculation of diffraction mtensittes in the scattering of atoms from a rigid crystal with a soft interaction potential. A general expression is derived for the diffraction intensities which can be applied to potentials with several higher-order terms in the Fourier series. For an uncorrugated Morse potential with a first-order exponential corrugation term an analytic solution is obtained which is compared with the infinite order suddent (10s) approximation calculations for Ne/W(llO) and He/LiF(lOO). Both approximations are very accurate for the weakly corrugated Ne/W system. For He/LiF the present approximation is more accurate than the sudden (10s) approximation and has the added advantage of providing an analytic solution. Several improvements are suggested.
Kinetic Energy Operators
Multidimensional Quantum Dynamics, 2009
Potential Representations (potfit)
Multidimensional Quantum Dynamics, 2009
MCTDH for Density Operator
Multidimensional Quantum Dynamics, 2009
Preparation of the Initial Wavepacket
Multidimensional Quantum Dynamics, 2009
Basic MCTDH Theory
Multidimensional Quantum Dynamics, 2009
Resonances of HCO Computed Using an Approach Based on the Multiconfiguration Time-Dependent Hartree Method
The journal of physical chemistry. A, Jan 24, 2015
The improved relaxation method with a complex absorbing potential (CAP) was used to compute reson... more The improved relaxation method with a complex absorbing potential (CAP) was used to compute resonance states of the formyl radical (HCO) using the Heidelberg multi-configuration time-dependent Hartree (MCTDH) program. To benchmark this approach, the same potential energy surface as was used in three other method development studies was used here. It was found that the MCTDH-based approach was able to accurately and efficiently compute 90 resonance states up to more than 1 eV above the dissociation limit. Extremely close agreement was obtained for energies and widths (lifetimes) calculated using MCTDH compared with those reported previously for three other CAP-based approaches that separately involved filter-diagonalization, a preconditioned complex-symmetric Lanczos algorithm, and a non-Hermitian real-arithmatic Lanczos method. The high accuracy achieved in this benchmark study supports the applicability of MCTDH to the study of resonances in larger systems in which increased dimens...
Wiley Interdisciplinary Reviews: Computational Molecular Science
Physical Review A, 2008
We study the ground states of one-dimensional Bose-Bose mixtures under harmonic confinement. As w... more We study the ground states of one-dimensional Bose-Bose mixtures under harmonic confinement. As we vary the inter-species coupling strength up to the limit of infinite repulsion, we observe a generalized, compositefermionization crossover. The initially coexisting phases demix as a whole (for weak intra-species interactions) and separate on an atomic level (for strong intra-species repulsion). By symmetry, the two components end up with strongly overlapping profiles, albeit sensitive to symmetry-breaking perturbations. Different pathways emerge in case the two components have different atom numbers, different intra-species interactions, or different masses and/or trap frequencies.
High Performance Computing in Science and Engineering '09, 2010
The Heidelberg Multiconfiguration Time-Dependent Hartree code is parallelized using shared-memory... more The Heidelberg Multiconfiguration Time-Dependent Hartree code is parallelized using shared-memory-techniques. A parallelization scheme based on a scheduler-worker approach is introduced. The performance of the parallel code is evaluated by benchmark tests. The infrared absorption spectrum of the protonated water dimer (H5O2+) is simulated in full dimensionality (15D) in the spectral range 0-4000 cm-1. The calculations are performed using the Multiconfiguration Time-Dependent Hartree (MCTDH) method for propagation of wavepackets. The middle spectral region, between 800 and 2000 wavenumbers is discussed and the couplings that shape this region of the spectrum are identified and explained, and the corresponding spectral lines assigned.
Vibrational Spectroscopy and Molecular Dynamics
Physical Chemistry in Action, 2013
Adiabatic Approximations for Molecules In Magnetic Fields
Chemistry in Space, 1990
Ultracold Few-Boson Systems in Traps
Multidimensional Quantum Dynamics, 2009
The Journal of chemical physics, Jan 28, 2014
Employing the multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) method in conjuncti... more Employing the multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) method in conjunction with the multistate multimode vibronic coupling Hamiltonian (MMVCH) model, we perform a full dimensional (9D) quantum dynamical study on the simplest Criegee intermediate, formaldehyde oxide, in five lower-lying singlet electronic states. The ultraviolet (UV) spectrum is then simulated by a Fourier transform of the auto-correlation function. The MMVCH model is built based on extensive MRCI(8e,8o)/aug-cc-pVTZ calculations. To ensure a fast convergence of the final calculations, a large number of ML-MCTDH test calculations is performed to find an appropriate multilayer separations (ML-trees) of the ML-MCTDH nuclear wave functions, and the dynamical calculations are carefully checked to ensure that the calculations are well converged. To compare the computational efficiency, standard MCTDH simulations using the same Hamiltonian are also performed. A comparison of the MCTDH and ML-MCTDH c...
The journal of physical chemistry. A, Jan 16, 2010
The gas-phase photoelectron spectrum of water in the 12-20 eV energy range is simulated. The pote... more The gas-phase photoelectron spectrum of water in the 12-20 eV energy range is simulated. The potential energy surfaces (PESs) of the three cationic states involved show several degeneracies. The ground state (X(2)B(1)) and the first excited state (A(2)A(1)) are degenerate components of a (2)Pi(u) state in linear geometry leading to Renner-Teller coupling while the PESs of the A state and the second excited state (B(2)B(2)) exhibit a conical intersection. Thus, an adiabatic approach that relies on sufficiently separated surfaces deems inappropriate. However, an orthogonal transformation of the electronic states removes the diverging matrix elements in the kinetic energy. These diabatic states permit a correct treatment of the nuclear dynamics near a conical intersection as well as in the Renner-Teller zone. The quantum mechanical equations of motion of the nuclei are solved using the multiconfiguration time-dependent Hartree (MCTDH) method. Quantum chemical calculations for the catio...
The Journal of Chemical Physics, 2014
For computational rovibrational spectroscopy the choice of the frame is critical for an approxima... more For computational rovibrational spectroscopy the choice of the frame is critical for an approximate separation of overall rotation from internal motions. To minimize the coupling between internal coordinates and rotation, Eckart proposed a condition ["Some studies concerning rotating axes and polyatomic molecules," Phys. Rev. 47, 552-558 (1935)] and a frame that fulfills this condition is hence called an Eckart frame. A method is developed to introduce in a systematic way the Eckart frame for the expression of the kinetic energy operator (KEO) in the polyspherical approach. The computed energy levels of a water molecule are compared with those obtained using a KEO in the standard definition of the Body-fixed frame of the polyspherical approach. The KEO in the Eckart frame leads to a faster convergence especially for large J states and vibrationally excited states. To provide an example with more degrees of freedom, rotational states of the vibrational ground state of the trans nitrous acid (HONO) are also investigated. © 2014 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4895557] j κ (Q κ , t) = J A J J ,
The Journal of chemical physics, Jan 21, 2007
We present the results of a full-dimensional quantum mechanical study of the rovibrational energy... more We present the results of a full-dimensional quantum mechanical study of the rovibrational energy transfer in the collision between ortho-H2 and para-H2 in the energy range of 0.1-1.0 eV. The multiconfiguration time-dependent Hartree algorithm has been used to propagate the wave packets on the global potential energy surface by Boothroyd et al. [J. Chem. Phys. 116, 666 (2002)] and on a modification of this surface where the short range anisotropy is reduced. State-to-state attributes such as probabilities or integral cross sections are obtained using the formalism of Tannor and Weeks [J. Chem. Phys. 98, 3884 (1993)] by Fourier transforming the correlation functions. The effect of initial rotation of the diatoms on the inelastic and de-excitation processes is investigated.
Physical review. A, Jan 15, 1989
Uploads
Papers by Hans-dieter Meyer