def get_hessian(self):
force_const = self.fields.get("<STR_LIT>")<EOL>if force_const is None:<EOL><INDENT>return None<EOL><DEDENT>N = len(self.molecule.numbers)<EOL>result = np.zeros((<NUM_LIT:3>*N, <NUM_LIT:3>*N), float)<EOL>counter = <NUM_LIT:0><EOL>for row in range(<NUM_LIT:3>*N):<EOL><INDENT>result[row, :row+<NUM_LIT:1>] = force_const[counter:counter+row+<NUM_LIT:1>]<EOL>result[:row+<NUM_LIT:1>, row] = force_const[counter:counter+row+<NUM_LIT:1>]<EOL>counter += row + <NUM_LIT:1><EOL><DEDENT>return result<EOL>
Return the hessian