potentials/tersoff.h

   1 /*
   2  * tersoff.h - tersoff potential header file
   3  *
   4  * author: Frank Zirkelbach <frank.zirkelbach@physik.uni-augsburg.de>
   5  *
   6  */
   7
   8 #ifndef TERSOFF_H
   9 #define TERSOFF_H
  10
  11 #define TERSOFF_MAXN    16*27
  12
  13 /* tersoff exchange type */
  14 typedef struct s_tersoff_echange {
  15
  16         t_3dvec dist_ij;
  17         double d_ij2;
  18         double d_ij;
  19
  20         t_3dvec dist_ik[TERSOFF_MAXN];
  21         double d_ik2[TERSOFF_MAXN];
  22         double d_ik[TERSOFF_MAXN];
  23
  24         double f_c_ik[TERSOFF_MAXN];
  25         double df_c_ik[TERSOFF_MAXN];
  26
  27         double g[TERSOFF_MAXN];
  28         double dg[TERSOFF_MAXN];
  29         double cos_theta[TERSOFF_MAXN];
  30
  31         double *beta_i;
  32         double *n_i;
  33         double *c_i;
  34         double *d_i;
  35         double *h_i;
  36
  37         double ci2;
  38         double di2;
  39         double ci2di2;
  40         double betaini;
  41
  42         double zeta_ij;
  43         double pre_dzeta;
  44
  45         int kcount;
  46 } t_tersoff_exchange;
  47
  48 /* tersoff mult (2!) potential parameters */
  49 typedef struct s_tersoff_mult_params {
  50         double S[2];            /* tersoff cutoff radii */
  51         double S2[2];           /* tersoff cutoff radii squared */
  52         double R[2];            /* tersoff cutoff radii */
  53         double Smixed;          /* mixed S radius */
  54         double S2mixed;         /* mixed S radius squared */
  55         double Rmixed;          /* mixed R radius */
  56         double A[2];            /* factor of tersoff attractive part */
  57         double B[2];            /* factor of tersoff repulsive part */
  58         double Amixed;          /* mixed A factor */
  59         double Bmixed;          /* mixed B factor */
  60         double lambda[2];       /* tersoff lambda */
  61         double lambda_m;        /* mixed lambda */
  62         double mu[2];           /* tersoff mu */
  63         double mu_m;            /* mixed mu */
  64
  65         double chi;
  66
  67         double beta[2];
  68         double n[2];
  69         double c[2];
  70         double d[2];
  71         double h[2];
  72
  73         t_tersoff_exchange exchange;    /* exchange between 2bp and 3bp calc */
  74 } t_tersoff_mult_params;
  75
  76 /* function prototypes */
  77 int tersoff_mult_set_params(t_moldyn *moldyn,int element1,int element2);
  78 int tersoff_mult_1bp(t_moldyn *moldyn,t_atom *ai);
  79 int tersoff_mult_2bp(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc);
  80 int tersoff_mult_3bp_j1(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc);
  81 int tersoff_mult_3bp_k1(t_moldyn *moldyn,
  82                         t_atom *ai,t_atom *aj,t_atom *ak,u8 bc);
  83 int tersoff_mult_3bp_j2(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc);
  84 int tersoff_mult_3bp_k2(t_moldyn *moldyn,
  85                         t_atom *ai,t_atom *aj,t_atom *ak,u8 bc);
  86 int tersoff_mult_check_2b_bond(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc);
  87
  88 /* tersoff potential paramter defines */
  89
  90 // silicon
  91 #define TM_R_SI                 2.7                             /* A */
  92 #define TM_S_SI                 3.0                             /* A */
  93 #define TM_A_SI                 (1830.8*EV)                     /* NA */
  94 #define TM_B_SI                 (471.18*EV)                     /* NA */
  95 #define TM_LAMBDA_SI            2.4799                          /* 1/A */
  96 #define TM_MU_SI                1.7322                          /* 1/A */
  97 #define TM_BETA_SI              1.1000e-6
  98 #define TM_N_SI                 0.78734
  99 #define TM_C_SI                 1.0039e5
 100 #define TM_D_SI                 16.217
 101 #define TM_H_SI                 -0.59825
 102
 103 // carbon
 104 #define TM_R_C                  1.8                             /* A */
 105 #define TM_S_C                  2.1                             /* A */
 106 #define TM_A_C                  (1393.6*EV)                     /* NA */
 107 #define TM_B_C                  (346.7*EV)                      /* NA */
 108 #define TM_LAMBDA_C             3.4879                          /* 1/A */
 109 #define TM_MU_C                 2.2119                          /* 1/A */
 110 #define TM_BETA_C               1.5724e-7
 111 #define TM_N_C                  0.72751
 112 #define TM_C_C                  3.8049e4
 113 #define TM_D_C                  4.384
 114 #define TM_H_C                  -0.57058
 115
 116 // mixed: silicon carbide
 117 #define TM_CHI_SIC              0.9776
 118 #define TM_LC_SIC               4.32                            /* A */
 119
 120 #endif