New Formulation and Implementation of Vibrational Self-Consistent Field Theory

Hansen, Mikkel B.
Sparta, Manuel
Seidler, Peter
Toffolı, Danıele
Christiansen, Ove
A new implementation of the vibrational self-consistent field (VSCF) method is presented on the basis of a second quantization formulation. A so-called active terms algorithm is shown to be a significant improvement over a standard implementation reducing the computational effort by one order in the number of degrees of freedom. Various types of screening provide even further reductions in computational scaling and absolute CPU time. VSCF calculations on large polyaromatic hydrocarbon model systems are presented. Further, it is demonstrated that in cases where distant modes are not directly coupled in the Hamiltonian, down to linear scaling of the required CPU time with respect to the number of vibrational modes can be obtained. This is illustrated with calculations on simple model systems with up to 1 million degrees of freedom.


Questioning Degree of Accuracy Offered by the Spectral Element Method in Computational Electromagnetics
Mahariq, I.; KURT, HAMZA; Kuzuoğlu, Mustafa (2015-07-01)
In this paper, a comparison amongst the spectral element method (SEM), the finite difference method (FDM), and the first-order finite element method (FEM) is presented. For the sake of consistency, the comparison is carried out on one-dimensional and two-dimensional boundary value problems based on the same measure of error in order to emphasize on the high accuracy gained by the SEM. Then, the deterioration in the accuracy of the SEM due to the elemental deformation is demonstrated. Following this, we try ...
A new time-domain boundary element formulation for generalized models of viscoelasticity
Akay, Ahmet Arda; Gürses, Ercan; Göktepe, Serdar (2023-05-01)
The contribution is concerned with the novel algorithmic formulation for generalized models of viscoelasticity under quasi-static conditions within the framework of the boundary element method (BEM). The proposed update algorithm is constructed for a generic rheological model of linear viscoelasticity that can either be straightforwardly simplified to recover the basic Kelvin and Maxwell models or readily furthered towards the generalized models of viscoelasticity through the serial or parallel extensions. ...
Evaluation of Hypersingular Integrals on Non-planar Surfaces
Selcuk, Gokhun; Koç, Seyit Sencer (2014-05-16)
Solving electric field integral equation (EFIE) with Nystrom method requires accurate evaluation of hypersingular surface integrals since this method does not use divergence conforming basis and testing functions. The success of the method also depends on accurate representation of non-planar characteristics of the scattering object. In this study Hadamard finite part interpretation is used to evaluate hypersingular integrals over non-planar surfaces, which are represented by their Taylor series expansions....
Efficient Computation of Green's Functions for Multilayer Media in the Context of 5G Applications
Mittra, Raj; Özgün, Özlem; Li, Chao; Kuzuoğlu, Mustafa (2021-03-22)
This paper presents a novel method for effective computation of Sommerfeld integrals which arise in problems involving antennas or scatterers embedded in planar multilayered media. Sommerfeld integrals that need to be computed in the evaluation of spatial-domain Green's functions are often highly oscillatory and slowly decaying. For this reason, standard numerical integration methods are not efficient for such integrals, especially at millimeter waves. The main motivation of the proposed method is to comput...
Alıyev, Tahmasıb; PAK, NK (1994-11-15)
The path integral representation for the propagator of a spinning particle in an external electromagnetic field is derived using the functional derivative formalism with the help of a Weyl symbol representation. The proposed method essentially simplifies the proof of the path integral representation starting from the equation for the Green function and automatically leads to a precise and unambiguous form of the boundary conditions for the Grassmann variables and puts a strong restriction on the choice of t...
Citation Formats
M. B. Hansen, M. Sparta, P. Seidler, D. Toffolı, and O. Christiansen, “New Formulation and Implementation of Vibrational Self-Consistent Field Theory,” JOURNAL OF CHEMICAL THEORY AND COMPUTATION, pp. 235–248, 2010, Accessed: 00, 2020. [Online]. Available: