This code example, written in C++, demonstrates how to implement a simple MP2 program using MPQC. This example
demonstrates how to extend MPQC Wavefunction class to implement new quantum chemical methods.

1) To compile this example you must have compiled MPQC and installed it using 'make install'
   commmand. This will install the code examples under $prefix/doc/share/mpqc-${version}/examples directory, where $prefix is the
   installation prefix provided to configure script during configuration of MPQC
   (the default is /usr/local/mpqc/$mpqcversion).
2) To compile the mp2 example simply type 'make', this will create an executable file called 'mp2'. To run it simply type './mp2 ./mp2.in'.
3) To compare the MP2 energy against that obtained with MPQC, simply change class name from MP2 to MBPT2 in 'mp2.in', and run mpqc as 'mpqc ./mp2.in'.
