Letters of invitation can be sent by the secretariat on request. These do not imply acceptance of abstracts or funding by the organisers of the conference.
The visa regulations can be found at the website of the federal foreign office.
EU nationals do not require a visum to enter the Federal Republic of Germany.
Generally speaking, all other foreigners require a visa for stays in Germany. A visum is not required for semi-annual visits of up to three months for nationals of those countries for which the European Community has abolished the visa requirement.