config_reset Subroutine

   subroutine config_reset(this)
      !! Reset all configuration values to defaults
      class(method_config_t), intent(inout) :: this

      ! Common settings
      this%method_type = METHOD_TYPE_UNKNOWN
      this%verbose = .false.
      this%basis_set = 'sto-3g'
      this%use_spherical = .true.

      ! XTB defaults
      this%xtb%accuracy = 0.01_dp
      this%xtb%electronic_temp = 300.0_dp
      this%xtb%solvent = ''
      this%xtb%solvation_model = ''
      this%xtb%use_cds = .true.
      this%xtb%use_shift = .true.
      this%xtb%dielectric = -1.0_dp
      this%xtb%cpcm_nang = 110
      this%xtb%cpcm_rscale = 1.0_dp

      ! SCF defaults (shared by HF and DFT)
      this%scf%max_iter = 100
      this%scf%energy_convergence = 1.0e-8_dp
      this%scf%density_convergence = 1.0e-6_dp
      this%scf%use_diis = .true.
      this%scf%diis_size = 8

      ! DFT-specific defaults
      this%dft%functional = 'b3lyp'
      this%dft%grid_type = 'medium'
      this%dft%radial_points = 75
      this%dft%angular_points = 302
      this%dft%use_density_fitting = .false.
      this%dft%aux_basis_set = ''
      this%dft%use_dispersion = .false.
      this%dft%dispersion_type = 'd3bj'

      ! MCSCF defaults
      this%mcscf%n_active_electrons = 0
      this%mcscf%n_active_orbitals = 0
      this%mcscf%n_inactive_orbitals = -1
      this%mcscf%n_states = 1
      if (allocated(this%mcscf%state_weights)) deallocate (this%mcscf%state_weights)
      this%mcscf%max_macro_iter = 100
      this%mcscf%max_micro_iter = 50
      this%mcscf%orbital_convergence = 1.0e-6_dp
      this%mcscf%ci_convergence = 1.0e-8_dp
      this%mcscf%use_pt2 = .false.
      this%mcscf%pt2_type = 'nevpt2'
      this%mcscf%ipea_shift = 0.25_dp
      this%mcscf%imaginary_shift = 0.0_dp

      ! Correlation defaults (shared by MP2, CC, etc.)
      this%corr%energy_convergence = 1.0e-8_dp
      this%corr%n_frozen_core = -1
      this%corr%freeze_core = .true.
      this%corr%use_df = .true.
      this%corr%aux_basis = ''
      this%corr%use_local = .false.
      this%corr%local_type = 'dlpno'
      this%corr%pno_threshold = 1.0e-7_dp
      this%corr%use_scs = .false.
      this%corr%scs_ss = 1.0_dp/3.0_dp
      this%corr%scs_os = 1.2_dp

      ! Coupled-cluster defaults
      this%cc%max_iter = 100
      this%cc%amplitude_convergence = 1.0e-7_dp
      this%cc%include_triples = .false.
      this%cc%perturbative_triples = .true.
      this%cc%use_diis = .true.
      this%cc%diis_size = 8
      this%cc%n_roots = 0
      this%cc%eom_type = 'ee'

      ! F12 defaults
      this%f12%geminal_exponent = 1.0_dp
      this%f12%ansatz = '3c'
      this%f12%cabs_basis = ''
      this%f12%optri_basis = ''
      this%f12%use_exponent_fit = .false.
      this%f12%scale_triples = .true.
   end subroutine config_reset