A canonical approach to multi-dimensional van der waals, hydrogen-bonded, and halogen-bonded potentials

A canonical approach is used to investigate prototypical multi-dimensional intermolecular interaction potentials characteristic of categories in van der Waals, hydrogen-bonded, and halogen-bonded intermolecular potential energy functions. It is demonstrated that well-characterized potentials in Ar-HI, OC-HI, OC-HF, and OC-BrCl, can be canonically transformed to a common dimensionless potential with relative error less than 0.010. The results indicate common intrinsic bonding properties despite other varied characteristics in the systems investigated. The results of these studies are discussed in the context of the previous statement made by J. C. Slater [J. Chem. Phys. 57 (1972) 2389] concerning fundamental bonding properties in the categories of interatomic interactions analyzed

Incorporation of a rovibrational analysis of oc-h2o into 6-d morphed potentials of the complex

Rovibrational transitions associated with tunneling states in the water bending vibration in OC-H$_2$O and other available spectroscopic data are included in generation of 6-D morphed potentials of the complex. Six-dimension \textit{ab initio} interaction potentials are initially calculated for the complex to provided the initial functions for the potential morphing. The available spectroscopic data is then used to fit and generate 6-D morphed potentials. Previous prediction of the \textit{D}$_0$ of the complex will be incorporated in the analysis. Finally, intermolecular frequencies of the complex will be predicted using the 6-D morphed potentials involving the CO stretching and the H$_2$O bending vibrations

Genetic, agronomic and compositional characterization of brown midrib sweet sorghum lignocellulosic biomass for ethanol production

Sorghum is a promising bioenergy crop due to its unique phenotypic and genotypic attributes. Quality (low lignin and high stem sugar concentration) and quantity (biomass yield, plant height, plant maturity, etc.) biomass traits are key contributors to ethanol yield and production. In this study, a 236 sorghum recombinant inbred line (RIL) population was subjected to genetic, agronomic and compositional characterization for ethanol yield and production. We found that the sweet mutation enhances biomass quantity traits in the RILs which translates to higher ethanol production and biomass quality which improves ethanol yield. The variance components showed from moderate to high heritability for biomass quantity and quality traits. The variability observed in most of these traits was due mainly to genetic effects. Correlations showed positive associations between biomass quantity traits and stem sugar concentration (SSC). These results indicate that selection for multiple traits could increase ethanol production. Single marker analysis showed two possible quantitative trait loci, on chromosomes 6 and 7, explaining only 2 and 7% of the variation in SSC measurements. ^ The brown midrib mutation in this population was previously identified in the caffeic acid-O-methyltransferase (COMT) gene resulting in reduced lignin content. A useful InDel marker for the mutant allele of COMT was identified for this population. Fiber detergent analysis (FDA) was performed to estimate the amount of hemicellulose, cellulose and lignin. Glucose recovery and theoretical ethanol yield and production were calculated and differences among grouped RILs analyzed. Only RILs carrying the brown midrib mutation showed significantly higher glucose recovery, those carrying both compositional mutations, showed significantly higher ethanol yields, and those with double mutations or the sweet mutation had significantly higher theoretical ethanol production. Lignin (R2= 0.66) was identified as the most reliable predictor for glucose recovery. Lignin and SSC (R2= 0.46 and 0.35, respectively) were identified as good predictors for ethanol yield. Dry stover and fresh stover yield (R 2= 0.89) were the most appropriate predictors for ethanol production. ^ Additionally, a nitrogen experiment was conducted to study the effect of four nitrogen rates on biomass traits of nine sorghum varieties, as lines and hybrids with and without brown midribs, a sweet and a photoperiod sensitive cultivar and a maize hybrid. Nitrogen application rate had significant effects on biomass components. The grain sorghum hybrid and the grain maize hybrid maximized grain yields across nitrogen rates. The photoperiod sensitive and sweet sorghums maximized stover yields across nitrogen rates. Maximum grain yield was obtained at 135kg N ha-1, while maximum stover yield was 67kg N ha-1. Across genotypes, grain nitrogen use efficiency (NUE) ranged from 19 to 50kg kg-1, while stover NUE ranged from 31 to 125kg kg-1. The dual-purpose sorghum hybrid showed the highest grain NUE, while the sweet sorghum showed the highest stover NUE. This research suggests that targeted improvement of biomass quantity and quality traits, and nitrogen management could increase ethanol production

Economic Integration and Endogenous Growth

In a world with two similar, developed economies, economic integration can cause a permanent increase in the worldwide rate of growth. Starting from a position of isolation, closer integration can be achieved by increasing trade in goods or by increasing flows of ideas. We consider two models with different specifications of the research and development sector that is the source of growth. Either form of integration can increase the long-run rate of growth if it encourages the worldwide exploitation of increasing returns to scale in the research and development sector.

International Trade with Endogenous Technological Change

To explain why trade restrictions sometimes speed up worldwide growth and sometimes slow it down, we exploit an analogy with the theory of consumer behavior. substitution effects make demand curves slope down, but income effects can increase or decrease the slope, and can sometimes overwhelm the substitution effect. We decompose changes in the worldwide growth rate into two effects (integration and redundancy) that unambiguously slow down growth, and a third effect (allocation) that can either speed it up or slow it down. We study two types of trade restrictions to illustrate the use of this decomposition. The first is across the board restrictions on traded goods in an otherwise perfect market. The second is selective protection of knowledge-intensive goods in a world with imperfect intellectual property rights. In both examples, we show that for trade between similar regions such as Europe and North America, the first two effects dominate; starting from free trade, restrictions unambiguously reduce worldwide growth.

RELAXATION OF VIBRATIONAL, ROTATIONAL, AND CORIOLIS ENERGIES OF AN EXCITED NITROMETHANE MOLECULE IN ARGON BATH

Our previous work [Rivera-Rivera \textit{et al. J. Chem. Phys.} 142, 014303 (2015)] used classical molecular dynamics simulations to study the pressure effects on the relaxation of a nitromethane (CH$_{3}$NO$_{2}$) molecule in an argon bath at 300 K and pressure ranging from 10 to 400 atm. The molecule was instantaneously excited by statistically distributing 50 kcal/mol among all its internal degrees of freedom. The saved CH$_{3}$NO$_{2}$ positions and momenta are then used to separate the vibrational and rotational energy of the molecule following the methodology developed by Rhee and Kim [\textit{J. Chem. Phys.} 107, 1394 (1997)]. The vibrational, rotational, and Coriolis energies exhibited multi-exponential decay. It is also found, that at later times the three energies decay approximately exponentially with similar decay rates. The mode-specific decomposition of these three energies produces, for each of the eight studied pressures, approximately 30 separate decay curves whose signal rises above statistical noise. Which vibrational and rotational modes these decay curves represent, and how their pressure dependence varies, gives insight into how excess energy equilibrates in CH$_{3}$NO$_{2}$

COMPOUND-MODEL MORPHED POTENTIAL FOR THE HYDROGEN BOND HCN–HF

A five-dimensional compound-model morphed potential has been generated for the prototype hydrogen-bonded dimer HCN-HF. The potential includes the intermolecular degree of freedom and the HF stretching vibration. Five morphing parameters only are optimized correcting for inadequacies in the underlying \textit{ab initio} potentials. The morphing transformation utilized a rotationally resolved spectroscopic database composed of microwave and infrared spectroscopic information. Band origin fundamental vibrational frequencies in HCN-HF are fitted to an average absolute error of 0.006 \wn. The calculated value of the ground state dissociation energy, \textit{D}$_{0}$ = 1969 \wn is in excellent agreement with the experimental value of 1970(10) \wn [Oudejans and Miller, Chem. Phys. 239 (1998) 345]. Limitations of the morphing methodology and its potential applications will be discussed

Morphed Potential Energy Surfaces from the Spectroscopy of Weakly Bound Complexes

In this research the so-called potential morphing method was used to generate reliable interaction potential energy surfaces for weakly bound complexes. The potential morphing method is based on the optimization of modified computed ab initio potential energy surfaces to give predicted spectroscopic data, in agreement with the experimental values. In the standard potential morphing procedure the computed ab initio potential is adjusted by scaling, shifting, and dilating transformations to reproduce the experimental data. In this research, selected systems have been chosen to be studied based on the availability of varied and accurate sets of experimental data. In the present work, accurate interaction potential energy surfaces are obtained for the weakly bound complexes: Ne:HCl, OC:HX (X = F, Cl, Br, I) and HI:CO2. A comprehensive study on the interaction potential of these systems provides fundamental perspectives on the influence of different intermolecular forces. In addition the ground state isotopic isomerization observed in the OC:HI system may suggest a possible structural change of proteins, and other biological macromolecules, in deuterated solvents. In this dissertation, an alternative approach to morphing the potential energy surfaces of non-covalent interactions is also presented. In this approach the morphed potential is generated as a linear combination of ab initio potentials, that are computed at different levels of theory. This new morphing approach is applied to OC:HCl and is found to be of similar accuracy to that of the previous morphing method. In addition, this new method is also extended from four-dimensions to six-dimensions and is applied to the OC:HF system to obtain a vibrationally-complete six-dimensional morphed potential

A CANONICAL APPROACH TO GENERATE MULTIDIMENSIONAL POTENTIAL ENERGY SURFACES

Previously adaptions of canonical approaches were applied to algebraic forms of the classic Morse, Lennard-Jones, and Kratzer potentials. Using the classic Morse, Lennard-Jones, or Kratzer potential as reference, inverse canonical transformations allow the accurate generation of Born-Oppenheimer potentials for H$_2$$^+$ ion, neutral covalently bound H$_2$, van der Waals bound Ar$_2$, and the hydrogen bonded 1-dimensional dissociative coordinate in water dimer. This methodology is now extending to multidimensional potential energy surfaces, and as a proof-of-concept, it is applied to the 3-dimensional water molecule potential surface. Canonical transformations previously developed for diatomic molecules are used to construct accurate approximations to the 3-dimensional potential surface of the water molecule from judiciously chosen 1-dimensional planar slices that are shown to have the same canonical shape as the classical Lennard-Jones potential curve. Spline interpolation is then used to piece together the 1-dimensional canonical potential curves, to obtain the full 3-dimensional potential surface of water molecule with a relative error less than 0.008

A ROVIBRATIONAL ANALYSIS OF THE WATER BENDING VIBRATION IN OC-H2O AND A MORPHED POTENTIAL OF THE COMPLEX

Rovibrational transitions associated with tunneling states in the water bending vibration in OC-H$_2$O complex have been recorded using a supersonic jet quantum cascade laser spectrometer at 6.2 $mu$m. Analysis of the resulting spectra is facilitated by incorporating fits of previously recorded microwave and submillimeter data accounting for Coriolis coupling to obtain the levels of the ground vibrational state. The results were then used to confirm assignment of the vibration and explore the nature of tunneling dynamics in associated vibrationally excited states of the complex. A seven-dimension textit{ab initio} interaction potential is constructed for the complex. The available spectroscopic data is used to generated a morphed potential. Previous prediction of the $D_0$ of the complex will be incorporated in the analysis