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  • 1
    Online Resource
    Online Resource
    Walter de Gruyter GmbH ; 2020
    In:  Cybernetics and Information Technologies Vol. 20, No. 6 ( 2020-12-01), p. 201-212
    In: Cybernetics and Information Technologies, Walter de Gruyter GmbH, Vol. 20, No. 6 ( 2020-12-01), p. 201-212
    Abstract: Combining a computationally efficient and affordable molecular dynamics approach, based on atom-centered density matrix propagation scheme, with the density functional tight binding semiempirical quantum mechanics, we study the vibrational dynamics of a single molecule at series of finite temperatures, spanning quite wide range. Data generated by molecular dynamics simulations are further analyzed and processed using time series analytic methods, based on correlation functions formalism, leading to both vibrational density of states spectra and infrared absorption spectra at finite temperatures. The temperature-induced dynamics in structural intramolecular parameters is correlated to the observed changes in the spectral regions relevant to molecular detection. In particular, we consider a case when an intramolecular X-H stretching vibrational states are notably dependent on the intramolecular torsional degree of freedom, the dynamics of which is, on the other hand, strongly temperature-dependent.
    Type of Medium: Online Resource
    ISSN: 1314-4081
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2020
    detail.hit.zdb_id: 2860325-4
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  • 2
    Online Resource
    Online Resource
    Scalable Computing: Practice and Experience ; 2018
    In:  Scalable Computing: Practice and Experience Vol. 19, No. 2 ( 2018-05-10), p. 119-130
    In: Scalable Computing: Practice and Experience, Scalable Computing: Practice and Experience, Vol. 19, No. 2 ( 2018-05-10), p. 119-130
    Abstract: Vibrational spectra of the two conformers of the free formic acid molecule are computed by two approaches, with a special emphasis on the region of O-H stretching modes. The first approach (referred to as a static one) is based on sequential computation of anharmonic O-H stretching vibrational potential and numerical solution of the vibrational Schr\"{o}dinger equation by the Numerov method. The second approach (referred to as a dynamic one) is based on molecular dynamics (MD) simulations performed within the atom-centered density matrix propagation scheme (ADMP) followed by spectral analysis of the velocity-velocity and dipole moment autocorrelation functions computed from the ADMP MD trajectories. All calculations are carried out within the density functional tight binding (DFTB) formalism. The computed properties are compared to the available experimental data and the advantages of the dynamic versus the static approach are outlined and analyzed in the context of detection of individual and non-covalently bonded molecular species relevant to climate science and atmospheric chemistry.
    Type of Medium: Online Resource
    ISSN: 1895-1767
    Language: Unknown
    Publisher: Scalable Computing: Practice and Experience
    Publication Date: 2018
    detail.hit.zdb_id: 2240223-8
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  • 3
    Online Resource
    Online Resource
    World Scientific Pub Co Pte Ltd ; 2018
    In:  International Journal of Software Engineering and Knowledge Engineering Vol. 28, No. 03 ( 2018-03), p. 407-425
    In: International Journal of Software Engineering and Knowledge Engineering, World Scientific Pub Co Pte Ltd, Vol. 28, No. 03 ( 2018-03), p. 407-425
    Abstract: This paper presents a novel quality model, which provides a quantitative assessment of the attributes evaluated at each stage of development of scientific applications. This model is defined by selecting a set of attributes and metrics that affect the quality of applications. It is based on the established quality standards. The practical application and verification of the quality model is confirmed by two case studies. The first is an application for solving one-dimensional and two-dimensional Schrödinger equations, using the discrete variables representation method. The second is an application for calculating an ECG-derived heart rate and respiratory rate. The first application follows a development model for scientific applications, which includes some software engineering practices. The second application does not use a specific development model, rather, it is developed ad hoc. The quality of the applications is evaluated through comparative analyses using the proposed model. Based on software quality metrics, the results of this study indicate that the application for solving one-dimensional and two-dimensional Schrödinger equations produces more desirable results.
    Type of Medium: Online Resource
    ISSN: 0218-1940 , 1793-6403
    Language: English
    Publisher: World Scientific Pub Co Pte Ltd
    Publication Date: 2018
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  • 4
    Online Resource
    Online Resource
    Scalable Computing: Practice and Experience ; 2018
    In:  Scalable Computing: Practice and Experience Vol. 19, No. 2 ( 2018-05-10), p. 149-159
    In: Scalable Computing: Practice and Experience, Scalable Computing: Practice and Experience, Vol. 19, No. 2 ( 2018-05-10), p. 149-159
    Abstract: In the present study, a molecular dynamics study of irinotecan molecule with the atom-centered density matrix propagation scheme was carried out at AM1 semiempirical level of theory, at series of different temperatures, ranging from 5 K to 300 K. Molecular dynamics simulations were performed within the NVE ensemble, initially injecting (and redistributing among the nuclei) various amounts of nuclear kinetic energies to achieve the desired target temperatures. Subsequently to initial equilibration phase of 2 ps, productive simulations were carried out for 8 ps. The accuracy of simulations and the closeness of the generated trajectory to those at the Born-Oppenheimer surface were carefully followed and analyzed. To compute the temperature-dependent rovibrational density of states spectra, the velocity-velocity autocorrelation functions were computed and Fourier-transformed. Fourier-transformed dipole moment autocorrelation functions were, on the other hand, used to calculate the temperature-dependent infrared absorption cross section spectra. The finite-temperature spectra were compared to those computed by a static approach, i.e. by diagonalization of mass-weighted Hessian matrices at the minima located on the potential energy surfaces. Thermally-induced spectral changes were analyzed and discussed. The advantages of finite-temperature statistical physics simulations based on semiempirical Hamiltonian over the static semiempirical ones in the case of complex, physiologically active molecular systems relevant to intermolecular interactions between drugs and drug carriers were pointed out and discussed.
    Type of Medium: Online Resource
    ISSN: 1895-1767
    Language: Unknown
    Publisher: Scalable Computing: Practice and Experience
    Publication Date: 2018
    detail.hit.zdb_id: 2240223-8
    Library Location Call Number Volume/Issue/Year Availability
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