Ulrich Müller-Herold

Extracting elements of molecular structure from the all-particle wave function

Structural information is extracted from the all-particle (non-Born-Oppenheimer) wave function by calculating radial and angular densities derived from n-particle densities. As a result, one- and two-dimensional motifs of classical molecular structure can be recognized in quantum mechanics. Numerical examples are presented for three- (H(-), Ps(-), H(2)(+)), four- (Ps(2), H(2)), and five-particle (H(2)D(+)) systems.

A closed analytical formula for the characteristic spatial range of persistent organic pollutants

Abstract In order to use mobility as a criterion for priority setting amongst environmental chemicals the characteristic spatial range of a substance has been introduced. Roughly spoken, the spatial range is the typical distance a chemical can travel before degradation — after release from a point source in an isotropic environment with the same average geo-chemical properties as the earth. The present contribution starts with a formal definition of spatial ranges in terms of exposure. Then a simple isotropic model of global circulation is set up in analogy to previous unit-world models, covering global long-range transport and (pseudo-)first-order degradation. Afterwards, the model is solved analytically, and a closed formula for spatial range is obtained. The formula is then evaluated for a selection of representative environmental chemicals. The characteristic spatial ranges thus obtained are identical with results obtained by M. Scheringer on the basis of a more detailed computer model. It is stressed that the present result allows for a classification of environmental chemicals with respect to spatial range simply by inserting known measurable quantities into a given formula. The whole approach was designed to make the assessment procedure as workable as possible.

Fragments of an Algebraic Quantum Mechanics Program for Theoretical Chemistry

In the winter semester 1978/79, Hans Primas organized a remarkable weekly seminar entitled “Great Unsolved Problems in Chemistry”. He invited along all his colleagues from the renowned chemistry department of the ETH in Zurich. The issue under discussion was: What are the basic problems — from a contemporary point of view — in chemistry as an academic science, i.e., not directed towards practical application? For however successful chemistry may seem to the outside world, and however much it can point to glorious successes, chemists themselves fall silent when the subject arises of the genuinely scientific open questions in their field. This is in sharp contrast to biology and physics, where even the students are aware of unsolved basic questions.

The Primas Effect: On Quanta and Beyond

A university committee meeting. The discussion getting nowhere very fast. Old, familiar facts are being trotted out, with nothing more than slight variations, now and then. Progress has come to a halt; the air hangs heavier and heavier. Sometime, at long last, Hans Primas takes the floor. Suddenly the problem appears to be transformed. There is a breath of fresh air, and the whole discussion takes a totally different turn. Such is the Primas effect. The term was coined by Konrad Osterwalder, the quantum field theorist who, having observed the Primas effect, officially coined this term on 9th November 1995.

Theoretical Chemistry and More: Personal Annotations to Hans Primas and His Work

In the mid 1960s, Hans Primas concentrated on research into the enigmatic relation between chemistry and quantum mechanics: How can a molecule exhibit purely classical features as in stereochemical ball-and-stick models alongside purely quantal properties as in chemical spectroscopy? Due to the discovery of superselection rules in the 1950s Primas was able to propose a solution in terms of classical observables. In this vein he contributed to the theory of chirality and to the measurement problem of quantum mechanics. In addition, he initiated research on elementary systems and the construction of observables in general. At the end of the 1970s, a permanent discussion topic in the Primas group was reductionism: How can a given theoretical description be related to more fundamental lower-level theories? Primas’ magnum opus Chemistry, Quantum Mechanics and Reductionism of 1981 addresses this question, which is difficult and controversial at the same time. After his retirement, Primas restarted earlier work on time and irreversibility. This culminated in a seminal paper on “Time-Entanglement between Mind and Matter” in 2003 that explores Wolfgang Pauli’s idea that mind and matter are complementary aspects of the same reality.

Zweites Beispiel: Fermi’s Golden Rule und Einsteins Übergangswahrscheinlichkeiten

Mit Hilfe der in Kapitel. 4 entwickelten linearen Antworttheorie lassen sich in transparenter Weise Fermis Golden Rule und die Einsteinschen Ubergangswahrscheinlichkeiten diskutieren.

Dynamik offener Systeme

Jedes naturwissenschaftlich relevante System ist in eine Umgebung eingebettet. Im strengsten Sinne isolierte und mit ihrer Umgebung nicht korrelierte Systeme gibt es nicht. Trotzdem ist diese Fiktion eines isolierten Systems der Ausgangspunkt der Hamiltonschen Mechanik. Modifikationen werden nachtrah vorgenommen, indem man sich vorstellt, man konne das uns interessierende System durch Hinzunahme seiner Umgebung zu einem strikte isolierten System erganzen. Auf diese Weise kann man jedenfalls versuchen, zu einer relevanten Dynamik fur das uns interessierende Teilsystem zu kommen.

Die lineare Antwort thermischer Quantensysteme

In der modernen chemischen Spektroskopie werden die klassischen Methoden der elektronischen Signalubertragung auf quantenmechanische Systeme angewendet. Zunachst werden dazu die ingenieurtheoretischen Grundlagen entwickelt, bis dann in Abschn. 4.6 die Brucke zu den quantenmechanischen Anwendungen geschlagen werden kann.

Dichteoperatoren zur Beschreibung offener Systeme

Alle Systeme, welche in den Naturwissenschaften betrachtet werden, sind offene Systeme. Wenn wir irgend etwas in der Natur beschreiben wollen, mussen wir die Welt in zwei Teile separieren: In das System, das wir eigentlich beschreiben mochten, und seine Umgebung, d. h. den Rest der Welt. Die Umgebungseffekte fuhren unter anderem zu Relaxationseffekten und zu spektroskopischen Linienverbreiterungen. Um die Einfuhrung von Dichteoperatoren zu motivieren, untersuchen wir, wie die Beschreibung aussieht, wenn wir auch die Umgebung des Systems in die Betrachtung einbeziehen.

Einleitende Bemerkungen Über die Theoretischen Grundlagen der Chemie

Von einer guten Theorie erwarten wir, dass sie empirisch richtig logisch konsistent anschaulich praktisch brauchbar ist.