The Associate Shell is composed of high-level research groups that develop theory and software in the area of electronic excitations (see the ETSF groups). These groups join the scientific community created around the ETSF, and may contribute significantly to the services of the ETSF and benefit from its outreach work. The members of the Core and of the Associate Shell assess each new request for membership of the Associate Shell on the basis of scientific excellence and reliability; membership of the ETSF must be a sign of high scientific quality.
Members of the Associate Shell benefit fully from the scientific exchange that is made possible and driven forward by the ETSF. They can advertise on the ETSF web site and call for proposals (see below) just like members of the Core; however, they do not increase the administrative overhead of the ETSF since all financial business is treated separately. In particular, when an Associate Shell group takes up a project after recommendation by the scientific board (see below), it will be directly in contact with the group that has requested the service, and the two partners will stipulate the corresponding contract.
Members of Associated groups are likely to make both direct contributions to the activities of the ETSF, and indirect contributions--sometimes only as Users. Generally it will be expected that Associated groups will arrange their own funding for their own research, but some ETSF funding may be available for research in collaboration with the Core, travel related to ETSF activities, participation in the annual conference and other workshops, and so on.
When a specific service is commissioned from the Core by an Associated group, this must be paid for by the group as a User. Such funds may be used to provide materials or personnel as required. However, an Associated group may also be involved in the provision of such services, and in these circumstances would expect to receive funding in order to provide them on behalf of the ETSF.
An annual conference, as well as other ETSF-related events, will bring members of the Core and Associate Shells together.