A Russian visa is an official permit to enter, pass through, stay in, or live in Russia for a certain period of time. It is a document in the form of an endorsement placed in your passport by a Russian Embassy or Consulate in your country of residence.

There are several categories and types of visas depending on the purpose of visit.
To take part in the conference or scientific program organized by the PDMI/EIMI you should obtain an "ordinary humanitarian" visa, as the purpose of your trip will be "scientific-technical relations".

a) passport which is valid at least for 6 months after your trip to Russia,

b) two empty pages (without any stamps, messages, etc.) in your passport, facing each other, one of which will be used for your visa to be pasted upon,

c) the original letter of invitation (LOI) issued by the PDMI or by the Russian Federal Migration Service, depending on the agreement on visa entry signed between the Russian Federation and the country of your citizenship.

d) If you plan to apply for a visa in a country that is not the country of your citizenship, you must also have a valid residence permit in the country of residence. Do not forget find out the validity of the residence permit for the visa obtaining purpose in the Russian consulate in advance.

The whole process of obtaining the visa you can find in Step-by-step instruction.