The Ontology of Quantum Chemistry

Sebastián Fortín, Martín Labarca, Olímpia Lombardi

Juan Camilo Martínez González

Quantum chemistry is the branch of chemistry whose primary focus is the application of quantum mechanics to chemical systems at the molecular level. Precisely due to its peculiar position between chemistry and physics, in the last times it has begun to engage the interest of the philosophers of chemistry. Nevertheless, in this philosophical field, quantum chemistry has been studied mainly from a historical viewpoint or from a perspective interested on methodological issues. By contrast, the question that will guide this article is: what kind of ontic items are those studied by quantum chemistry? In order to develop the argumentation, first the relevance of the ontological questions will be addressed. Then, it will be considered in what measure the Born-Oppenheimer approximation and the quantum-chemistry concept of electron fit in the quantum theoretical context. Finally, some issues about what quantum chemistry refers to will be discussed.

Per‐Olov Löwdin

Sebastián Fortín, Olímpia Lombardi

Abstract Despite the successful development of quantum chemistry, the deep breakdown between the conceptual basis of standard quantum mechanics and some implicit ontological assumptions of quantum chemistry is only rarely acknowledged. In fact, in the framework of standard quantum mechanics, quantum systems are not individual objects in the philosophical sense: they cannot be individualized by their positions in space and time and, as a consequence, they have no trajectories. By contrast, the basic magnitude in quantum chemistry is the electronic density, which is commonly interpreted in terms of the definite positions occupied by the individual electron in its motion around the nucleus. In the present paper, it will be argued that Bohmian Mechanics offers an ontological picture that is much closer to the quantum chemists’ way of conceiving their research field.

Linus Carl Pauling