Critical analysis of fragment-orbital DFT schemes for the calculation of electronic coupling values

We present a critical analysis of the popular fragment-orbital density-functional theory (FO-DFT) scheme for the calculation of electronic coupling values. We discuss the characteristics of different possible formulations or 'flavors' of the scheme which differ by the number of electrons in the calculation of the fragments and the construction of the Hamiltonian. In addition to two previously described variants based on neutral fragments, we present a third version taking a different route to the approximate diabatic state by explicitly considering charged fragments. In applying these FO-DFT flavors to the two molecular test sets HAB7 (electron transfer) and HAB11 (hole transfer) we find that our new scheme gives improved electronic couplings for HAB7 (-6.2% decrease in mean relative signed error) and greatly improved electronic couplings for HAB11 (-15.3% decrease in mean relative signed error). A systematic investigation of the influence of exact exchange on the electronic coupling values shows that the use of hybrid functionals in FO-DFT calculations improves the electronic couplings, giving values close to or even better than more sophisticated constrained DFT calculations. Comparing the accuracy and computational cost of each variant we devise simple rules to choose the best possible flavor depending on the task. For accuracy, our new scheme with charged-fragment calculations performs best, while numerically more efficient at reasonable accuracy is the variant with neutral fragments

Register Classification by Timbre

The aim of this analysis is the demonstration that the high and the low musical register (Soprano, Alto vs. Tenor, Bass) can be identified by timbre, i.e. after pitch information is eliminated from the spectrum. This is achieved by means of pitch free characteristics of spectral densities of voices and instruments, namely by means of masses and widths of peaks of the first 13 partials (cp. Weihs and Ligges (2003b)). Different analyses based on the tones in the classical song ?Tochter Zion? composed by G.F. Händel are presented. Results are very promising. E.g., if the characteristics are averaged over all tones, then female and male singers can be easily distinguished without any error (prediction error of 0%)! Moreover, stepwise linear discriminant analysis can be used to separate even the females together with 28 high instruments (?playing? the Alto version of the song) from the males together with 20 low instruments (playing the Bass version) with a prediction error of 4%. Also, individual tones are analysed, and the statistical results are discussed and interpreted from acoustics point of view. --

Register Classification by Timbre

The aim of this analysis is the demonstration that the high and the low musical register (Soprano, Alto vs. Tenor, Bass) can be identified by timbre, i.e. after pitch information is eliminated from the spectrum. This is achieved by means of pitch free characteristics of spectral densities of voices and instruments, namely by means of masses and widths of peaks of the first 13 partials (cp. Weihs and Ligges (2003b)). Different analyses based on the tones in the classical song "Tochter Zion" composed by G.F. Händel are presented. Results are very promising. E.g., if the characteristics are averaged over all tones, then female and male singers can be easily distinguished without any error (prediction error of 0%)! Moreover, stepwise linear discriminant analysis can be used to separate even the females together with 28 high instruments ("playing" the Alto version of the song) from the males together with 20 low instruments (playing the Bass version) with a prediction error of 4%. Also, individual tones are analysed, and the statistical results are discussed and interpreted from acoustics point of view

Commentary on "An Exploratory Study of Western Orchestration: Patterns through History" by S.H. Chon, D. Huron, & D. DeVlieger

This commentary discusses the exploratory study by Chon, Huron and DeVlieger about the usage and combinations of musical instruments in orchestral works between 1700 and 2000 under the perspective of the evolution of the musical instruments in that time, their acoustical and social aspects as well as recommendations in orchestration treatises of the last 300 years

Modellvorstellungen über Klangfarbe: Von der »Manichfaltigkeit der Praedicate« zum Timbre Space

What are the timbral characteristics of musical sounds? From the second half of the nineteenth century, ideas about musical timbre were affected by contradictory and platitude statements that have lead researchers and musicians throughout history to adopt various models and perspectives. However, the influence of pitch and dynamics has largely been ignored within these models by definition. Another fact had further effects on the history of psychoacoustical research: While Hermann von Helmholtz’s Lehre von den Tonempfindungen was soon translated into English by Alexander J. Ellis, a translation of Carl Stumpf’s standard works Tonpsychologie (1883 and 1890) and Die Sprachlaute (1926) has yet to be published, as are translations of the important writings of other German-speaking successors to Helmholtz and Stumpf (such as Köhler, Schumann, Albersheim, Reinecke, Fricke etc.). Consequently, Anglo-American psychoacoustical research, which has been most influential in this field since World War II, is lacking this particular aspect of knowledge about musical timbre. The relevance of the German research tradition comes to light when we examine an instrument in its entire pitch and dynamic range (rather than only one or a few pitches as in most timbre studies): timbre perception of musical instruments is determined to a certain extent by steady pitch-independent formant areas, whose origin and characteristics at pitch and dynamic changes has generally been resolved today. These timbral effects appear to be in accordance with the principles of Auditory Scene Analysis (Albert S. Bregman) as well as with recommendations in orchestration treatises of the last centuries. Anglo-American models, such as John Grey’s Timbre Space and subsequent research, and German models of timbre perception both have advantages and short- coming. With the help of sound analysis and re-synthesis software and in combination with the concept of mel-frequency cepstral coefficients methods, it seems possible to merge these diverse approaches into a common timbre perception model

'Warriors of the Word' -- Deciphering Lyrical Topics in Music and Their Connection to Audio Feature Dimensions Based on a Corpus of Over 100,000 Metal Songs

We look into the connection between the musical and lyrical content of metal music by combining automated extraction of high-level audio features and quantitative text analysis on a corpus of 124.288 song lyrics from this genre. Based on this text corpus, a topic model was first constructed using Latent Dirichlet Allocation (LDA). For a subsample of 503 songs, scores for predicting perceived musical hardness/heaviness and darkness/gloominess were extracted using audio feature models. By combining both audio feature and text analysis, we (1) offer a comprehensive overview of the lyrical topics present within the metal genre and (2) are able to establish whether or not levels of hardness and other music dimensions are associated with the occurrence of particularly harsh (and other) textual topics. Twenty typical topics were identified and projected into a topic space using multidimensional scaling (MDS). After Bonferroni correction, positive correlations were found between musical hardness and darkness and textual topics dealing with 'brutal death', 'dystopia', 'archaisms and occultism', 'religion and satanism', 'battle' and '(psychological) madness', while there is a negative associations with topics like 'personal life' and 'love and romance'.Comment: Corrected typo in abstract (subsample

A versatile scanning photocurrent mapping system to characterize optoelectronic devices based on 2D materials

The investigation of optoelectronic devices based on two-dimensional materials and their heterostructures is a very active area of investigation with both fundamental and applied aspects involved. We present a description of a home-built scanning photocurrent microscope that we have designed and developed to perform electronic transport and optical measurements of two-dimensional materials based devices. The complete system is rather inexpensive (<10000 EUR) and it can be easily replicated in any laboratory. To illustrate the setup we measure current-voltage characteristics, in dark and under global illumination, of an ultra-thin PN junction formed by the stacking of an n-doped few-layer MoS2 flake onto a p-type MoS2 flake. We then acquire scanning photocurrent maps and by mapping the short circuit current generated in the device under local illumination we find that at zero bias the photocurrent is generated mostly in the region of overlap between the n-type and p-type flakes.Comment: 9 pages, 3 figures, 1 table, supporting informatio

Guide to the galaxy of EU regional funds recipients: evidence from new data

This study presents a new firm- and project-level dataset containing data on over two million projects co-funded by the EU structural and cohesion funds in 25 EU member states during the programming period 2007-2013. Information on individual beneficiary firms and institutions is linked with business data of Bureau van Dijk's ORBIS database. Moreover, text mining techniques are applied to categorise the EU cohesion policy projects into fifteen thematic categories. Stylised facts reveal substantial regional heterogeneity in the distribution of funds to certain projects and beneficiaries (with respect to their size or industry). Furthermore, regional funds distribution differs across less developed and higher-income as well as urban and rural regions. In an econometric analysis, we control for project and firm characteristics that we expect to determine the single project's value, which is confirmed by the results. Nevertheless, there remains unexplained variation in individual project volumes, which differs systematically across countries