The Role of Trajectories in Quantum Chemistry and Chemical Physics

2012 ◽  
pp. 235-301
Author(s):  
Ángel Sanz ◽  
Salvador Miret-Artés
Keyword(s):  
Quantum Chemistry ◽  
Chemical Physics

On the Structure of Lead(II) Complexes in Aqueous Solutions. I. Trinuclear Clusters

1995 ◽  
Vol 60 (4) ◽  
pp. 527-536 ◽  
Author(s):  
Martin Breza ◽  
Alena Manová
Keyword(s):  
Quantum Chemistry ◽  
Aqueous Solutions ◽  
Electronic Structures ◽  
Mndo Method ◽  
Model Systems ◽  
Trinuclear Clusters ◽  
The Stability ◽  
Semiempirical Mndo

Using semiempirical MNDO method of quantum chemistry the optimal geometries and corresponding electronic structures of [Pb3(OH)n]6-n model systems as well as of their hydrated [Pb3(OH)n(H2O)8-n]6-n analogues (n = 4, 5) are investigated. The most stable trinuclear lead(II) complexes present in aqueous solutions correspond to cyclo-(μ3-OH)(μ2-OH)3Pb32+, Pb(μ-OH)2Pb(μ-OH)2Pb2+, cyclo-(μ3-OH)2(μ2-OH)3Pb3+, Pb(OH)(μ-OH)2Pb(μ-OH)Pb(OH)+ and Pb(OH)(μ-OH)2Pb(μ-OH)2Pb+ systems. The key role of OH bridges (by vanishing direct Pb-Pb bonds) on the stability of individual isomers is discussed.

Substance and Function

2020 ◽  
pp. 188-203
Author(s):  
Jean-Pierre Llored
Keyword(s):  
Quantum Chemistry ◽  
Philosophy Of Science ◽  
Periodic Table ◽  
Functional Role ◽  
Functional Approach ◽  
Different Types ◽  
And Function

This paper aims to analyze the two aspects of elements, material and conceptual, in order to further understand the functional role played by elements in chemistry. First, we will refer to how Mendeleev gradually built his periodic table. Second, we will both highlight and reflect upon the functional role of elements in chemistry. In doing so, we will refer in particular to Cassirer’s philosophy of science. In conclusion, we propose that a functional approach is important for understanding current chemical practice, especially in nanochemistry and quantum chemistry. This approach also contributes to the analysis of different types of mereology that coexist in chemistry today.

Philosophical Issues in (Sub)Disciplinary Contexts: The Case of Quantum Chemistry

2016 ◽  
Author(s):  
Kostas Gavroglu ◽  
Ana Simões
Keyword(s):  
Quantum Mechanics ◽  
Quantum Chemistry ◽  
Philosophical Problem ◽  
Ontological Status ◽  
Energy Resonance ◽  
Straightforward Application ◽  
History Of ◽  
Chemical Character ◽  
State Of Affairs

IN A WAY, QUANTUM chemistry was “born” as a philosophical problem: It was, of course, chemistry, but owed its scientific status to physics; it was physics with the promise of explaining all of chemistry. Thankfully, following P. A. M. Dirac’s verdict (1929), this state of affairs, at least some years after 1929, was for a future world, an almost utopian world. In the meantime, chemists, physicists, and mathematicians for about half a century defying Dirac’s soothing call that all is well, but only on principle, brought about a new subdiscipline and all the methodological, epistemological, and philosophical problems that go along with the formation of any subdiscipline. In this chapter we put forward a proposal as to how we can write the history of an “in-between” discipline such as quantum chemistry, suggesting that this proposal can be extended to other “in-between” disciplines. Then, we address the role of theory in chemistry, and specifically in quantum chemistry, including the issues surrounding the ontological status of theoretical entities, and proceed to discuss the implications of the introduction of computers in quantum chemistry and the concomitant reconceptualization of experiment. Finally, we reappraise the question of reductionism from the perspective of the practitioners of quantum chemistry. From the very beginning of the period when chemical problems were examined quantum mechanically, everyone involved in the subsequent developments tried to understand the chemical character of what was begotten in the encounter(s) of chemistry with quantum mechanics. Was quantum chemistry the subdiscipline for all those chemical problems formulated in the language of physics which could be dealt with by a straightforward application of quantum mechanics with, of course, the ensuing conceptual readjustments? Was it the case that chemical problems could be dealt with only through an intricate process of appropriation of quantum mechanics by the chemists’ culture? Furthermore, the development of quantum chemistry brought about new entities whose ontological status was continuously under negotiation: exchange energy, resonance, and orbitals were some of the more intriguing entities.

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