There is growing consensus that two key factors hinder progress in the field of approximate quantum dynamics:
1. Fragmentation of the research: several groups working on interesting and highly technical advances, but not enough opportunities to share information;
2. Lack of common benchmarks to assess merits and limitations of the different approaches and to identify the different areas of applicability.
These difficulties were recognized in particular during the workshop "Recent progress in adiabatic and non-adiabatic methods in quantum dynamics" held at CECAM HQ in May 2014. It was then suggested that the community should make an effort to set up an "infrastructure" to foster and possibly guide progress. As an integral part of this ongoing effort, we propose to:
1. Review, discuss, and compare in detail some of the available methods for (approximate) quantum propagation;
2. Consolidate the results of the discussion and make them available to the whole community by setting the stage for:
(a) writing a review of the methods discussed
(b) creating a web platform to host theoretical and computational information, including a guide to the available methods, tutorials and examples on the use of existing codes, and a test set of benchmarks (to be defined in the coming months and/or during the workshop).
To fulfill these goals, the format of this meeting will be different from a traditional workshop. During the first four days, a small group of volunteers (see program for names of lecturers who have agreed to participate) will present an overview on the following topics:
1. Exact and MCTDH methods
2. Path integral approaches (including semi-classical, initial value representation, ...)
3. Mixed quantum-classical (Wigner-Liouville, LANDMAP, but also Ehrenfest and trajectory surface hopping)
4. Trajectory based methods (Bohmian dynamics and exact factorization)
5. Ring polymer molecular dynamics
The overview will last 2.5/3 hours and describe (in a lecture format):
(a) The fundamentals and key development steps of the method from the basics to the recent developments;
(b) The advantages but also (importantly) the limits of the approach;
(c) The available implementations and codes.
When necessary, a 25 min. seminar describing some more advanced topics might be added within the time allocated to each lecture. These "lectures" are intended as a guide for discussion with the audience (composed mainly by experts in the field), the key element of each session. As such, this is not a school (though if possible it will be open to junior participants), but an opportunity to assess the state of the art and identify directions for developments.
The last day of the meeting will focus the previous work by:
1. Setting the stage for writing one (or more) review paper by writing an outline of contents and identifying, among volunteers from the speakers and the participants, the work groups/authors who will focus on different topics.
2. Presenting and further structuring the web platform for the quantum dynamics community. Ideally, this platform would then be maintained with the help of CECAM, but alternatives are available.