نتایج جستجو برای: semi empirical methods

تعداد نتایج: 2149770  

2014
Yvette Graham Timothy Baldwin

Automatic metrics are widely used in machine translation as a substitute for human assessment. With the introduction of any new metric comes the question of just how well that metric mimics human assessment of translation quality. This is often measured by correlation with human judgment. Significance tests are generally not used to establish whether improvements over existing methods such as B...

2003
Chin-Shan Chuang Ngai Hang Chan HANG CHAN

Empirical likelihood is developed for autoregressive models with innovations that form a martingale difference sequence. Limiting distributions of the log empirical likelihood ratio statistic for both the stable and unstable cases are established. Behavior of the log empirical likelihood ratio statistic is considered in nearly nonstationary models to assess the local power of unit root tests an...

2016
P. Chamorro-Posada

Semi-empirical quantum chemistry methods offer a very interesting compromise between accuracy and computational load. In order to assess the performance of NDDO methods in the interpretation of terahertz spectra, the low frequency vibration modes of three crystalline materials, namely, polyethylene, poly(vinylidene fluoride) form II and α-D-glucose have been studied using the PM6 and PM7 Hamilt...

2009
C. Casteleiro F. Parente P. Indelicato J. P. Marques

In this work we use the multiconfiguration Dirac-Fock method to calculate the transition probabilities for all possible decay channels, radiative and radiationless, of a K shell vacancy in Zn, Cd and Hg atoms. The obtained transition probabilities are then used to calculate the corresponding fluorescence yields which are compared to existing theoretical, semi-empirical and experimental results....

2014
Tomás Bouchal Radka Svobodová Vareková Tomás Racek Crina-Maria Ionescu Stanislav Geidl Ales Krenek Jaroslav Koca

Partial atomic charges describe the distribution of electron density in a molecule, and therefore they provide clues regarding the chemical behaviour of molecules. Atomic charges are frequently used in molecular modelling applications such as molecular dynamics, docking, conformational searches, binding site prediction, etc. Recently, partial atomic charges have also become popular chemoinforma...

2013
Walter Fabian

Equilibrium twist angles and rotational barriers for the three isomeric phenylpyrroles were calculated by means of MNDO and AMI. In each case MNDO incorrectly predicts the perpendicular conformation as the most stable one. In agreement with experimental evidence AMI predicts only slight deviations from planarity and very low 0°-barriers (1-phenylpyrrole: 0 = 28°, E = F6 kJ mol"; 2-phenylpyrrole...

2001
F.

efficient cyclization upon irradiation in acetonitrile to produce the spirocyclic enol ethers or esters 56-59. The ease of formation of the salts coupled with the exceptional chemical efficiencies and structural outcomes of these cyclizations indicates that this methodology will have synthetic utility. The results also demonstrate the importance of trialkylsilyl substituents in electrontransfer...

2017
Yixin Nie Mohit Bansal

We present a simple sequential sentence encoder for multi-domain natural language inference. Our encoder is based on stacked bidirectional LSTM-RNNs with shortcut connections and fine-tuning of word embeddings. The overall supervised model uses the above encoder to encode two input sentences into two vectors, and then uses a classifier over the vector combination to label the relationship betwe...

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