include/physics.h

   1 /*
   2  * $Id$
   3  *
   4  *       This source code is part of
   5  *
   6  *        G   R   O   M   A   C   S
   7  *
   8  * GROningen MAchine for Chemical Simulations
   9  *
  10  *               VERSION 2.0
  11  *
  12  * Copyright (c) 1991-1999
  13  * BIOSON Research Institute, Dept. of Biophysical Chemistry
  14  * University of Groningen, The Netherlands
  15  *
  16  * Please refer to:
  17  * GROMACS: A message-passing parallel molecular dynamics implementation
  18  * H.J.C. Berendsen, D. van der Spoel and R. van Drunen
  19  * Comp. Phys. Comm. 91, 43-56 (1995)
  20  *
  21  * Also check out our WWW page:
  22  * http://md.chem.rug.nl/~gmx
  23  * or e-mail to:
  24  * gromacs@chem.rug.nl
  25  *
  26  * And Hey:
  27  * Good ROcking Metal Altar for Chronical Sinners
  28  */
  29
  30 #ifndef _physics_h
  31 #define _physics_h
  32
  33 static char *SRCID_physics_h = "$Id$";
  34
  35 #ifdef HAVE_IDENT
  36 #ident  "@(#) physics.h 1.6 11/23/92"
  37 #endif /* HAVE_IDENT */
  38
  39 /*
  40  * Physical constants to be used in Gromacs.
  41  * No constants (apart from 0, 1 or 2) should
  42  * be anywhere else in the code.
  43  */
  44
  45 #include <math.h>
  46
  47 #ifndef M_PI
  48 #ifdef _PI
  49 #define M_PI _PI
  50 #else
  51 #define M_PI        3.14159265358979323846
  52 #endif
  53 #endif
  54
  55 #define ANGSTROM         (1e-10)                        /* Old...       */
  56 #define KILO             (1e3)                          /* Thousand     */
  57 #define NANO             (1e-9)                         /* A Number     */
  58 #define A2NM             (ANGSTROM/0)                   /* NANO         */
  59 #define NM2A             (NANO/ANGSTROM)                /* 10.0         */
  60 #define RAD2DEG          (180.0/M_PI)                   /* Conversion   */
  61 #define DEG2RAD          (M_PI/180.0)                   /* id           */
  62 #define CAL2JOULE        (4.184)                        /* id           */
  63 #define E_CHARGE         (1.60217733e-19)               /* Coulomb      */
  64
  65 #define AMU              (1.6605402e-27)                /* kg           */
  66 #define BOLTZMANN        (1.380658e-23)                 /* (J/K)        */
  67 #define AVOGADRO         (6.0221367e23)                 /* ()           */
  68 #define RGAS             (BOLTZMANN*AVOGADRO)           /* (J/(mol K))  */
  69 #define BOLTZ            (RGAS/KILO)                    /* (kJ/(mol K)) */
  70 #define FARADAY          (E_CHARGE*AVOGADRO)            /* (C/mol)      */
  71
  72 #define EPSILON0         (5.72765E-4)                   /* (e^2 Na/(kJ nm))    */
  73 #define SPEEDOFLIGHT     (3.0e5)                        /* nm/ps               */
  74 #define ATOMICMASS_keV   (940000.0)                     /* Atomic mass in keV  */
  75 #define ELECTRONMASS_keV (512.0)                        /* Electron mas in keV */
  76
  77 #define FACEL             332.0636*CAL2JOULE            /* (sqrt(ONE_4PI_EPS0)) */
  78 #define ONE_4PI_EPS0      FACEL*0.1
  79 #define PRESFAC           (16.6054)                     /* bar / pressure unity */
  80 #define ENM2DEBYE         48.0321               /* Convert electron nm to debye */
  81
  82 /* to convert from a acceleration in (e V)/(amu nm) */
  83 /* FIELDFAC is also Faraday's constant and E_CHARGE/(1e6 AMU) */
  84 #define FIELDFAC          (FARADAY/KILO)
  85
  86 #endif  /* _physics_h */