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 "gromacs/utility/real.h"
  39
  40 #ifdef __cplusplus
  41 extern "C" {
  42 #endif
  43
  44 /* Used with force switching or a constant potential shift:
  45  * rsw       = max(r - r_switch, 0)
  46  * force/p   = r^-(p+1) + c2*rsw^2 + c3*rsw^3
  47  * potential = r^-p + c2/3*rsw^3 + c3/4*rsw^4 + cpot
  48  * With a constant potential shift c2 and c3 are both 0.
  49  */
  50 typedef struct {
  51     real c2;
  52     real c3;
  53     real cpot;
  54 } shift_consts_t;
  55
  56 /* Used with potential switching:
  57  * rsw        = max(r - r_switch, 0)
  58  * sw         = 1 + c3*rsw^3 + c4*rsw^4 + c5*rsw^5
  59  * dsw        = 3*c3*rsw^2 + 4*c4*rsw^3 + 5*c5*rsw^4
  60  * force      = force*dsw - potential*sw
  61  * potential *= sw
  62  */
  63 typedef struct {
  64     real c3;
  65     real c4;
  66     real c5;
  67 } switch_consts_t;
  68
  69 typedef struct {
  70     int             cutoff_scheme;
  71
  72     /* VdW */
  73     int             vdwtype;
  74     int             vdw_modifier;
  75     real            rvdw;
  76     real            rvdw_switch;
  77     shift_consts_t  dispersion_shift;
  78     shift_consts_t  repulsion_shift;
  79     switch_consts_t vdw_switch;
  80     /* TODO: remove this variable, used for not modyfing the group kernels,
  81      * it is equal to -dispersion_shift->cpot
  82      */
  83     real sh_invrc6;
  84
  85     /* type of electrostatics (defined in enums.h) */
  86     int  eeltype;
  87     int  coulomb_modifier;
  88
  89     /* Coulomb */
  90     real rcoulomb;
  91
  92     /* Cut-off */
  93     real rlist;
  94
  95     /* PME/Ewald */
  96     real ewaldcoeff_q;
  97     real ewaldcoeff_lj;
  98     int  ljpme_comb_rule; /* LJ combination rule for the LJ PME mesh part */
  99     real sh_ewald;        /* -sh_ewald is added to the direct space potential */
 100     real sh_lj_ewald;     /* sh_lj_ewald is added to the correction potential */
 101
 102     /* Dielectric constant resp. multiplication factor for charges */
 103     real epsilon_r;
 104     real epsfac;
 105
 106     /* Constants for reaction-field or plain cut-off */
 107     real epsilon_rf;
 108     real k_rf;
 109     real c_rf;
 110
 111     /* Force/energy interpolation tables, linear in force, quadratic in V */
 112     real  tabq_scale;
 113     int   tabq_size;
 114     /* Coulomb force table, size of array is tabq_size (when used) */
 115     real *tabq_coul_F;
 116     /* Coulomb energy table, size of array is tabq_size (when used) */
 117     real *tabq_coul_V;
 118     /* Coulomb force+energy table, size of array is tabq_size*4,
 119        entry quadruplets are: F[i], F[i+1]-F[i], V[i], 0,
 120        this is used with single precision x86 SIMD for aligned loads */
 121     real *tabq_coul_FDV0;
 122
 123     /* Vdw force table for LJ-PME, size of array is tabq_size (when used) */
 124     real *tabq_vdw_F;
 125     /* Vdw energy table for LJ-PME, size of array is tabq_size (when used) */
 126     real *tabq_vdw_V;
 127     /* Vdw force+energy table for LJ-PME, size of array is tabq_size*4, entry
 128        quadruplets are: F[i], F[i+1]-F[i], V[i], 0, this is used with
 129        single precision x86 SIMD for aligned loads */
 130     real *tabq_vdw_FDV0;
 131
 132 } interaction_const_t;
 133
 134 #ifdef __cplusplus
 135 }
 136 #endif
 137
 138 #endif