2-Cocycles on the Lie algebras of generalized differential operators
  In a recent paper by Zhao and the author, the Lie algebras $A[D]=A\otimes F[D]$ of Weyl type were defined and studied, where $A$ is a commutative associative algebra with an identity element over a field $F$ of any characteristic, and $F[D]$ is the polynomial algebra of a commutative derivation subalgebra $D$ of $A$. In the present paper, the 2-cocycles of a class of the above Lie algebras $A[D]$ (which are called the Lie algebras of generalized differential operators in the present paper), with $F$ being a field of characteristic 0, are determined. Among all the 2-cocycles, there is a special one which seems interesting. Using this 2-cocycle, the central extension of the Lie algebra is defined. 
Yucai Su