experimental chemistry do have many similarities in terms of following the scientific method, but they also have epistemological differences. Maybe the most striking difference is that wet chemistry, in terms of physical effects, is all-inclusive; it is not possible to remove relativistic effects or the zero-point energy (to give a couple of examples) from the molecules in a real-life flask. On the contrary, computational chemistry requires a conscious and careful decision on whether these specific effects should be included in the virtual experiment. Omit them, and the chemistry will not be realistic; incorporate unnecessary effects, and the job may be intractable. In this perspective, we will describe one direction to add quantum effects, depending on the reach and requirements of the studied question. From the electronic to the nuclear wave function and beyond, the addition of deeper and deeper quantum effects must be sequentially and judiciously nested as a matryoshka doll.
experimental chemistry do have many similarities in terms of following the scientific method, but they also have epistemological differences. Maybe the most striking difference is that wet chemistry, in terms of physical effects, is all-inclusive; it is not possible to remove relativistic effects or the zero-point energy (to give a couple of examples) from the molecules in a real-life flask. On the contrary, computational chemistry requires a conscious and careful decision on whether these specific effects should be included in the virtual experiment. Omit them, and the chemistry will not be realistic; incorporate unnecessary effects, and the job may be intractable. In this perspective, we will describe one direction to add quantum effects, depending on the reach and requirements of the studied question. From the electronic to the nuclear wave function and beyond, the addition of deeper and deeper quantum effects must be sequentially and judiciously nested as a matryoshka doll.
This textbook introduces the reader to quantum theory and quantum chemistry. The textbook is meant for 2 nd – 3 rd year bachelor students of chemistry or physics, but also for students of related disciplines like materials science, pharmacy, and bioinformatics. At first, quantum theory is introduced, starting with experimental results that made it inevitable to go beyond classical physics. Subsequently, the Schrödinger equation is discussed in some detail. Some few examples for which the Schrödinger equation can be solved exactly are treated with special emphasis on relating the results to real systems and interpreting the mathematical results in terms of experimental observations. Ultimately, approximate methods are presented that are used when applying quantum theory in the field of quantum chemistry for the study of real systems like atoms, molecules, and crystals. Both the foundations for the different methods and a broader range of examples of their applications are presented. The textbook assumes no prior knowledge in quantum theory. Moreover, special emphasis is put on interpreting the mathematical results and less on an exact mathematical derivations of those. Finally, each chapter closes with a number of questions and exercises that help in focusing on the main results of the chapter. Many of the exercises include answers.
The rapid development of the chemical industry and science and new challenges in the field of health care put forward increased demands for the development of the theory of organic and inorganic chemistry, biochemistry and biophysics, the search and implementation of new modelling and analysis methods, and the improvement of technological processes. One of the safe and fast methods of researching the properties and behavior of new materials and tools is the modelling of relevant experiments, in particular, computer molecular modelling based on mathematical models. Modelling the interactions between micro and macromolecules at the quantum level allows us to manipulate the substances’ electronic, magnetic, optical and other characteristics and consider the possibilities of creating new chemical bonds, molecular structures, phase transitions, quantum states, and so on. Accordingly, the main idea of our research is to apply the technology of algebraic modelling and quantum-chemical apparatus for the simulation and verification of experiments in physics, chemistry, and biology areas. The use of formal algebraic methods allows proving properties and finding relevant scenarios for the effective analysis of the behavior of various objects in real-time, considering not individual scenarios but sets of possible behaviors. At this research stage, we have developed a methodology for formalization complex organic and inorganic substances, chemical processes and reactions based on the formalization of the interaction of atoms and molecules at the level of quantum interactions.
A fully revised edition of this book has now been completed and published on Amazon, with the following major features, improvements, and additions: EQT Detection Theory: The Universe Has Never Been Silent: One Hundred Questions on Quantum Reality, the Cosmos, and Consciousness is a wide-ranging popular science book built around one hundred fundamental questions about nature. It begins with a simple but profound puzzle: is spacetime a pre-existing container, or does it emerge from deeper physical relations? From there, the book moves through quantum mechanics, the origin of forces, dark matter, dark energy, the arrow of time, life, consciousness, artificial intelligence, future technologies, and the limits of scientific explanation. At the center of the book is Energy Quantum Theory (EQT), a speculative but structured research program that attempts to reinterpret physical reality through the language of frequency, phase, resonance, and the energy quantum density field (\rho_f). Rather than presenting EQT as a completed theory, the book treats it as a lens: a way of asking old questions differently and connecting phenomena that are usually discussed separately. Gravity, electromagnetism, dark matter, dark energy, life, and consciousness are explored as different expressions of frequency structures operating across different scales. The book is written with a strong commitment to intellectual honesty. Each question follows a clear pattern: first, it explains the real phenomenon and the genuine puzzle; then it summarizes the current state of mainstream physics; then it introduces the possible EQT perspective; then it states the cost, boundary, and failure conditions of that perspective; finally, it reflects on why the question matters. This structure allows readers to distinguish established science from conjecture, mechanism from metaphor, and testable prediction from philosophical speculation. The book does not claim that EQT has solved physics. On the contrary, it repeatedly emphasizes what remains unfinished: the complete mathematical form of the master equation, the rigorous derivation of the Standard Model, quantitative predictions for cosmology, and experimental tests of the proposed frequency–consciousness relation. Its central value lies not in offering final answers, but in cultivating a disciplined way of thinking: classify the level of a claim, examine its cost, and ask what evidence would overturn it. In this sense, the book is both a journey through modern physics and a reflection on how science should proceed. It invites readers to see the universe not as a silent machine, but as a vast field of rhythms—some already detected through light, radio waves, gravitational waves, and neural oscillations, and many others still beyond our instruments. The part we can hear is science; the part we have not yet heard is the future.
This article considers a partly philosophical question: What are the ontological and epistemological reasons for using quantum-like models or theories (models and theories based on the mathematical formalism of quantum theory) vs. classical-like ones (based on the mathematics of classical physics), in considering human thinking and decision making? This question is only partly philosophical because it also concerns the scientific understanding of the phenomena considered by the theories that use mathematical models of either type, just as in physics itself, where this question also arises as a physical question. This is because this question is in effect: What are the physical reasons for using, even if not requiring, these types of theories in considering quantum phenomena, which these theories predict fully in accord with the experiment? This is clearly also a physical, rather than only philosophical, question and so is, accordingly, the question of whether one needs classical-like or quantum-like theories or both (just as in physics we use both classical and quantum theories) in considering human thinking in psychology and related fields, such as decision science. It comes as no surprise that many of these reasons are parallel to those that are responsible for the use of QM and QFT in the case of quantum phenomena. Still, the corresponding situations should be understood and justified in terms of the phenomena considered, phenomena defined by human thinking, because there are important differences between these phenomena and quantum phenomena, which this article aims to address. In order to do so, this article will first consider quantum phenomena and quantum theory, before turning to human thinking and decision making, in addressing which it will also discuss two recent quantum-like approaches to human thinking, that by M. G. D'Ariano and F. Faggin and that by A. Khrennikov. Both approaches are ontological in the sense of offering representations, different in character in each approach, of human thinking by the formalism of quantum theory. Whether such a representation, as opposed to only predicting the outcomes of relevant experiments, is possible either in quantum theory or in quantum-like theories of human thinking is one of the questions addressed in this article. The philosophical position adopted in it is that it may not be possible to make this assumption, which, however, is not the same as saying that it is impossible. I designate this view as the reality-without-realism, RWR, view and in considering strictly mental processes as the ideality-without-idealism, IWI, view, in the second case in part following, but also moving beyond, I. Kant's philosophy.
In principle, it is possible to model any physical system exactly using quantum mechanics; in practice, it quickly becomes infeasible. Recognising this, Richard Feynman suggested that quantum systems be used to model quantum problems [1]. For example, the fundamental problem faced in quantum chemistry is the calculation of molecular properties, which are of practical importance in fields ranging from materials science to biochemistry. Within chemical precision, the total energy of a molecule as well as most other properties, can be calculated by solving the Schrödinger equation. However, the computational resources required to obtain exact solutions on a conventional computer generally increase exponentially with the number of atoms involved [1, 2]. In the late 1990’s an efficient algorithm was proposed to enable a quantum processor to calculate molecular energies using resources that increase only polynomially in the molecular size [2–4]. Despite the many different physical architectures that have been explored experimentally since that time—including ions, atoms, superconducting circuits, and photons—this appealing algorithm has not been demonstrated to date.
Time evolution of quantum systems is of interest in physics, in chemistry, and, more recently, in computer science. Quantum computers are suggested as one route to propagating quantum systems far more efficiently than ordinary numerical methods. In the past few years, researchers have actively been improving quantum simulation algorithms, especially those in second quantization. This work continues to advance the state-of-the-art by unifying several diverging approaches under a common framework. In particular, it highlights the similarities and differences of the first and second quantized algorithms which are usually presented in a distinct fashion. By combining aspects of the two approaches, this work moves towards an online second quantized algorithm operating within a single-Fock space. This paper also unifies a host of approaches to algorithmic quantum measurement by removing superficial differences. The aim of the effort is not only to give a high-level understanding of quantum simulation, but to move towards experimentally realizable algorithms with practical applications in chemistry and beyond.