src/gromacs/mdtypes/interaction_const.h

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  35 #ifndef GMX_MDTYPES_INTERACTION_CONST_H
  36 #define GMX_MDTYPES_INTERACTION_CONST_H
  37
  38 #include <memory>
  39 #include <vector>
  40
  41 #include "gromacs/mdtypes/md_enums.h"
  42 #include "gromacs/utility/alignedallocator.h"
  43 #include "gromacs/utility/basedefinitions.h"
  44 #include "gromacs/utility/real.h"
  45
  46 /* Used with force switching or a constant potential shift:
  47  * rsw       = max(r - r_switch, 0)
  48  * force/p   = r^-(p+1) + c2*rsw^2 + c3*rsw^3
  49  * potential = r^-p + c2/3*rsw^3 + c3/4*rsw^4 + cpot
  50  * With a constant potential shift c2 and c3 are both 0.
  51  */
  52 struct shift_consts_t
  53 {
  54     real c2;
  55     real c3;
  56     real cpot;
  57 };
  58
  59 /* Used with potential switching:
  60  * rsw        = max(r - r_switch, 0)
  61  * sw         = 1 + c3*rsw^3 + c4*rsw^4 + c5*rsw^5
  62  * dsw        = 3*c3*rsw^2 + 4*c4*rsw^3 + 5*c5*rsw^4
  63  * force      = force*dsw - potential*sw
  64  * potential *= sw
  65  */
  66 struct switch_consts_t
  67 {
  68     real c3;
  69     real c4;
  70     real c5;
  71 };
  72
  73 /* Convenience type for vector with aligned memory */
  74 template<typename T>
  75 using AlignedVector = std::vector < T, gmx::AlignedAllocator < T>>;
  76
  77 /* Force/energy interpolation tables for Ewald long-range corrections
  78  *
  79  * Interpolation is linear for the force, quadratic for the potential.
  80  */
  81 struct EwaldCorrectionTables
  82 {
  83     // 1/table_spacing, units 1/nm
  84     real                scale = 0;
  85     // Force table
  86     AlignedVector<real> tableF;
  87     // Energy table
  88     AlignedVector<real> tableV;
  89     // Coulomb force+energy table, size of array is tabq_size*4,
  90     // entry quadruplets are: F[i], F[i+1]-F[i], V[i], 0,
  91     // this is used with 4-wide SIMD for aligned loads
  92     AlignedVector<real> tableFDV0;
  93 };
  94
  95 /* The physical interaction parameters for non-bonded interaction calculations
  96  *
  97  * This struct contains copies of the physical interaction parameters
  98  * from the user input as well as processed values that are need in
  99  * non-bonded interaction kernels.
 100  *
 101  * The default constructor gives plain Coulomb and LJ interactions cut off
 102  * a 1 nm without potential shifting and a Coulomb pre-factor of 1.
 103  */
 104 struct interaction_const_t
 105 {
 106     int             cutoff_scheme = ecutsVERLET;
 107
 108     /* VdW */
 109     int                    vdwtype          = evdwCUT;
 110     int                    vdw_modifier     = eintmodNONE;
 111     double                 reppow           = 12;
 112     real                   rvdw             = 1;
 113     real                   rvdw_switch      = 0;
 114     struct shift_consts_t  dispersion_shift = { 0, 0, 0 };
 115     struct shift_consts_t  repulsion_shift  = { 0, 0, 0 };
 116     struct switch_consts_t vdw_switch       = { 0, 0, 0 };
 117     gmx_bool               useBuckingham    = false;
 118     real                   buckinghamBMax   = 0;
 119
 120     /* type of electrostatics */
 121     int  eeltype          = eelCUT;
 122     int  coulomb_modifier = eintmodNONE;
 123
 124     /* Coulomb */
 125     real rcoulomb        = 1;
 126     real rcoulomb_switch = 0;
 127
 128     /* PME/Ewald */
 129     real ewaldcoeff_q    = 0;
 130     real ewaldcoeff_lj   = 0;
 131     int  ljpme_comb_rule = eljpmeGEOM; /* LJ combination rule for the LJ PME mesh part */
 132     real sh_ewald        = 0;          /* -sh_ewald is added to the direct space potential */
 133     real sh_lj_ewald     = 0;          /* sh_lj_ewald is added to the correction potential */
 134
 135     /* Dielectric constant resp. multiplication factor for charges */
 136     real epsilon_r = 1;
 137     real epsfac    = 1;
 138
 139     /* Constants for reaction-field or plain cut-off */
 140     real epsilon_rf = 1;
 141     real k_rf       = 0;
 142     real c_rf       = 0;
 143
 144     // Coulomb Ewald correction table
 145     std::unique_ptr<EwaldCorrectionTables> coulombEwaldTables;
 146     /* Note that a Van der Waals Ewald correction table
 147      * of type EwaldCorrectionTables can be added here if wanted.
 148      */
 149 };
 150
 151 #endif