The analytical, full-dimensional, and global representation of the potential energy surface of NH(3) in the lowest adiabatic electronic state developed previously (Marquardt, R.; et al. J. Phys. Chem. B 2005, 109, 8439–8451) is improved by adjustment of parameters to an enlarged set of electronic energies from ab initio calculations using the coupled cluster method with single and double substitutions and a perturbative treatment of connected triple excitations (CCSD(T)) and the method of multireference configuration interaction (MRCI). CCSD(T) data were obtained from an extrapolation of aug-cc-pVXZ results to the basis set limit (CBS), as described in a previous work (Yurchenko, S.N.; et al. J. Chem. Phys 2005, 123, 134308); they cover the region around the NH3 equilibrium structures up to 20,000 hc cm(–1). MRCI energies were computed using the aug-cc-pVQZ basis to describe both low lying singlet dissociation channels. Adjustment was performed simultaneously to energies obtained from the different ab initio methods using a merging strategy that includes 10,000 geometries at the CCSD(T) level and 500 geometries at the MRCI level. Characteristic features of this improved representation are NH3 equilibrium geometry r(eq)(NH(3)) ≈ 101.28 pm, α(eq)(NH(3)) ≈ 107.03°, the inversion barrier at r(inv)(NH(3)) ≈ 99.88 pm and 1774 hc cm(–1) above the NH(3) minimum, and dissociation channel energies 41,051 hc cm(–1) (for NH(3) → ((2)B(2))NH(2) + ((2)S(1/2))H) and 38,450 hc cm(–1) (for NH(3) → ((3)Σ(–))NH +((1)Σ(g)(+))H(2)); the average agreement between calculated and experimental vibrational line positions is 11 cm(–1) for (14)N(1)H(3) in the spectral region up to 5000 cm(–1). A survey of our current knowledge on the vibrational spectroscopy of ammonia and its isotopomers is also given.
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http://dx.doi.org/10.1021/jp4016728 | DOI Listing |
ACS Energy Lett
January 2025
Department of Physics, Technical University of Denmark, Kongens Lynby 2800, Denmark.
We discuss the challenges associated with achieving high energy efficiency in electrochemical ammonia synthesis at near-ambient conditions. The current Li-mediated process has a theoretical maximum energy efficiency of ∼28%, since Li deposition gives rise to a very large effective overpotential. As a starting point toward finding electrocatalysts with lower effective overpotentials, we show that one reason why Li and alkaline earth metals work as N reduction electrocatalysts at ambient conditions is that the thermal elemental processes, N dissociation and NH desorption, are both facile at room temperature for these metals.
View Article and Find Full Text PDFInorg Chem
January 2025
Research Laboratory of Advanced Water and Wastewater Treatment Processes, Department of Applied Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz 51666-16471, Iran.
In the field of solar energy storage, photocatalytic ammonia production is a next-generation technology. The rapid recombination of charges and insignificant utilization of the sunlight spectrum are bottlenecks of effective photocatalytic N fixation. The introduction of impurities in the crystal lattice and the development of heterojunctions could effectively segregate carriers and improve the solar-light-harvesting capability, which can boost NH generation.
View Article and Find Full Text PDFTrop Anim Health Prod
January 2025
Animal Production Department, Faculty of Agriculture, Ain-Shams University, 68 Hadayek Shoubra, Cairo, 111241, Egypt.
This study was designed to evaluate the effect of substituting alfalfa hay with graded levels panicum maximum without or with graded levels of spirulina supplementation on rumen fermentation and nutrient degradability. The evaluation was achieved through an in vitro study, rumen fluid was obtained from adult sheep aged 2 years (fed clover hay), immediately after slaughter. Experimental diets were formulated as isonitrogenous and isocaloric and contained 40% forage.
View Article and Find Full Text PDFSci Rep
January 2025
ICAR-National Institute of Abiotic Stress Management, Baramati, Pune, 413115, India.
The fishmeal is boon for aquaculture production in this recent pollution and climate change era. However, the demand of fishmeal is enhancing in many folds which needs to find alternative to fishmeal in cheap price. The present investigation addresses these issues with quinoa husk (QH).
View Article and Find Full Text PDFSci Total Environ
January 2025
Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON, Canada. Electronic address:
Upgrading wastewater treatment plants (WWTPs) is a global practice for achieving increasingly stringent nutrient discharge objectives set by governments to accommodate population growth and reduce surface water pollution. However, associated downstream improvements in nutrient conditions are difficult to determine in nearshore regions of large aquatic ecosystems due to complex biophysical processes. We conducted a nine-year water quality study and analyzed the data using linear mixed models (LMMs) within a Before-After-Control-Impact (BACI) framework to assess effects of an upgrade to the Duffin Creek Water Pollution Control Plant (DCWPCP) on surface water nutrient conditions and proliferation of nuisance benthic algae (Cladophora glomerata) in nearshore Lake Ontario.
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