The ham Section of the Jaguar Input File

By using the ham section and setting the gen section calculation keyword ihamtyp to 3, you can specify the exact coefficients used to calculate the electronic energy for open shell calculations. The electronic energy is given by the equation

where the sums are over orbitals [22]. The number of electron pairs per orbital in each orbital i is indicated by f_i, which can be listed in the ham section, and the one-electron Hamiltonian for that orbital is given by h_ii. The terms a_ij and b_ij are coefficients which can also be specified in the ham section, and the J_ij and K_ij terms are Coulomb and exchange terms for pairs of orbitals i and j. Orbitals which have the same a_ij and b_ij coefficients and number of electron pairs f_i are considered to be in the same shell.

The first line in the ham section should indicate the number of core orbitals for the molecule. Next, each shell is described in turn. The first line of each shell description should contain two numbers, the first an integer indicating the number of orbitals in that shell, and the second a real number indicating f_i, the number of electron pairs in each orbital of that shell. The next line should contain the a_ij terms for any orbital in the shell, where j < i and j is not a core orbital. The last line describing the shell lists all b_ij terms for any orbital in the shell, where j < i and j is not a core orbital.