Slave-fermion approach for the 2-D systems of antiferromagnetically correlated electrons based on functional Schrodinger representation

We consider the functional Schrodinger representation in order to treat bot h the Heisenberg Hamiltonian and the t-J Hamiltonian for the two dimensiona l systems of antiferromagnetically correlated electrons at and near the hal f-filling. We demonstrate that the present theory exactly agrees with the c onventional theory for the exchange energy derived from the Heisenberg Hami ltonian. Tts extension to the t-J Hamiltonian is discussed. (C) 1999 Elsevi er Science B.V. AII rights reserved.