  Using the integral transformation, the field-theoretical Hamiltonian of the
statistical field theory of fluids is obtained, along with the microscopic
expressions for the coefficients of the Hamiltonian. Applying this approach to
the liquid-vapor interface, we derive an explicit analytical expression for the
surface tension in terms of temperature, density and parameters of
inter-molecular potential. We also demonstrate that a clear physical
interpretation may be given to the formal statistical field arising in the
integral transformation - it may be associated with the one-body local
microscopic potential. The results of the theory, lacking any ad-hoc or fitting
parameters are in a good agreement with available simulation data.
