Concept and objectives
Scientific research requires dissemination of findings and results. The aim of most scientists is that other people (be they other scientists, industry, government or the public) should learn of their work and use it. Science is therefore probably the most international of all human activities since it flourishes by transnational exchanges at all levels. These exchanges are so usual, so important and so productive that national boundaries become virtually transparent during the interactions between scientists. Today many of these exchanges are electronic with immense amounts of data being exchanged using all forms of modern information technology. This in turn requires scientists to adapt to conducting research with data that come in rapidly increasing quantities, varieties and modes of dissemination, often for purposes far more interdisciplinary than in the past. Accordingly, around the world ‘data centres' and other more loosely defined organisations of data producers and users are participating in a revolutionary transformation in the manner in which data is exchanged. The most favoured forum for communication is the World Wide Web, due to its ubiquity and democracy.

Current substantive issues of data handling and storage include traditional endemic problems of maintaining consistency among the data sets; providing pathways for researchers to find what data compilations are available and providing enough descriptive material (metadata) to enable researchers to use databases with due awareness of the limitations of the data. Recently the vast increases in the quantity of data, particularly in the observational sciences (such as astronomy) due to the automation of methods of data collection and compilation have highlighted the problems of data transmission (along e-pipe lines), data storage and data analysis (which still remains largely unautomated)

Whilst the above statements are endemic to all areas of science, it is particularly apparent in the field of atomic and molecular science. This field provides a wealth of data that is used and applied across a wide range of scientific and technological applications. Indeed the progress in many scientific and technological areas is underpinned by the availability of accurate quantitative information on the collisional properties and spectroscopic characteristics of interacting species Atomic and molecular data are indispensable for such diverse applications as astrophysics, atmospheric science, the development of fusion energy, semiconductor manufacturing and other plasma based technologies, the lighting industry, detection and remediation of pollutants (and increasingly the detection of explosives and biological agents as may be used in terrorism) and is essential for understanding many biological processes including modelling radiation damage in cellular systems for therapy treatment. Scientists working with atomic and molecular data are therefore providing foundation for the new era of research – the era of e-sciences. However it is widely recognised that there remain several major challenges to developing a robust and integrated
infrastructure that can be used by the widest possible user community. The existing problems can be divided into two categories: (1) data completeness and quality assessment and (2) data interface including problem specific tools for data mining. Today those issues are tackled by a number of data centres but they are highly focussed on specific applications and non-flexible. Thus, there is a strong need to:
     •  Develop close links between the user communities, the data producers and data centres based on modern technology.
     •  Establish better international coordination in order to promote atomic and molecule data compilation and database activities, avoid duplication of efforts and ensure the use of the best available data.

Many European groups are recognised for their excellence in the field of atomic and molecular science and are contributing to the measurement and calculation of atomic and molecular (AM) data feeding several databases and information services. In some cases, indeed, AM data producers already established large networks on the European scale, such as the European Theoretical Spectroscopy Facility (ETSF, http://www.etsf.eu), a project developed within the EU-funded Nanoquanta Network of Excellence (http://www.nanoquanta.eu).

Several major ERA scientific initiatives plan to use such services for their own objectives and needs (e.g. the planetary science community through the Europlanet I3-FP7, the astronomy community through Euro-VO I3-FP7, the fusion community (supported by ITER and EURATOM) and the radiation science community for modelling radiotherapy and effect of low doses on human health (supported by EURATOM and the Framework VII (Health) Programme ). However within these initiatives little financial support is/can be assigned to the interoperability of atomic and molecular data. Every time the same AM database is used for a new application, the output of the database has to be cumbersomely adapted. For example automatic tools for the visualisation of simulations of planetary and stellar or the interstellar medium are planned. These tools will require automatic access to different AM databases, cross-matching the retrieved data as well as checking of the quality of data. Yet, to date there is no coherent and sufficiently general infrastructure to perform such tasks.

The Virtual Atomic and Molecular Data Centre (VAMDC) aims at building such a secure, documented, flexible, easily accessible and interoperable e-infrastructure for AM data. The VAMDC will be built upon the expertise of existing AM databases, data producers and service providers with the specific aim of creating an infrastructure that on one hand can directly extract data from the existing depositories while one the other hand is sufficiently flexible to be tuned to the needs of a wide variety of users from academic, governmental, industrial communities or from general public both within and outside the ERA. The project will address the building of the core consortium, the deployment of the infrastructure and the development of specific software as well as providing a forum for training of potential users and dissemination across the ERA. It is expected that VAMDC becomes a European legal entity during the course of the project.

Central to this aim is the task of overcoming the current fragmentation of the EU atomic and molecular database community. VAMDC will accomplish it:
     •   through the development of the largest and most comprehensive atomic and molecular e-infrastructure to be shared, fed and expanded by all EU A&M scientists and
     •   by providing a major distributed European infrastructure which can be accessed, referenced and exploited by the wider European Research community.

In fulfilling these aims the VAMDC project will organise a series of Networking Activities (NAs) laying the foundations for a long-lasting and self-sustaining Infrastructure. NAs are specifically aimed at
     •   Engaging data providers
     •   Coordinating activities amongst existing database providers
     •   Ascertaining and responding to the needs of different user communities
     •   Providing training and awareness of the VAMDC across the international community and community of planetary sciences in Europe.

The main output of the VAMDC is the provision of the VAMDC e-science platform delivered through a set of three Service Activities (SAs) The interoperability and thus the building of an e-science platform on atomic and molecular data require both technical research and development activities as well as scientific involvement of the producers community in order to define specifications, to prepare and to document their data. VAMDC's Joint Research Activities (JRAs) will develop this infrastructure improving the breadth and quality of facilities, models, software tools and services offered.