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/*
*
* This source code is part of
*
* G R O M A C S
*
* GROningen MAchine for Chemical Simulations
*
* VERSION 3.2.0
* Written by David van der Spoel, Erik Lindahl, Berk Hess, and others.
* Copyright (c) 1991-2000, University of Groningen, The Netherlands.
* Copyright (c) 2001-2004, The GROMACS development team,
* check out http://www.gromacs.org for more information.
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* If you want to redistribute modifications, please consider that
* scientific software is very special. Version control is crucial -
* bugs must be traceable. We will be happy to consider code for
* inclusion in the official distribution, but derived work must not
* be called official GROMACS. Details are found in the README & COPYING
* files - if they are missing, get the official version at www.gromacs.org.
*
* To help us fund GROMACS development, we humbly ask that you cite
* the papers on the package - you can find them in the top README file.
*
* For more info, check our website at http://www.gromacs.org
*
* And Hey:
* Gromacs Runs On Most of All Computer Systems
*/
#ifndef _physics_h
#define _physics_h
/*
* Physical constants to be used in Gromacs.
* No constants (apart from 0, 1 or 2) should
* be anywhere else in the code.
*/
#include <math.h>
/* we do it anyway. */
#ifdef __cplusplus
extern "C" {
#endif
#ifndef M_PI
#ifdef _PI
#define M_PI _PI
#else
#define M_PI 3.14159265358979323846
#endif
#endif
#define ANGSTROM (1e-10) /* Old... */
#define KILO (1e3) /* Thousand */
#define NANO (1e-9) /* A Number */
#define PICO (1e-12) /* A Number */
#define A2NM (ANGSTROM/NANO) /* NANO */
#define NM2A (NANO/ANGSTROM) /* 10.0 */
#define RAD2DEG (180.0/M_PI) /* Conversion */
#define DEG2RAD (M_PI/180.0) /* id */
#define CAL2JOULE (4.184) /* id */
#define E_CHARGE (1.60217733e-19) /* Coulomb */
#define AMU (1.6605402e-27) /* kg */
#define BOLTZMANN (1.380658e-23) /* (J/K) */
#define AVOGADRO (6.0221367e23) /* () */
#define RGAS (BOLTZMANN*AVOGADRO) /* (J/(mol K)) */
#define BOLTZ (RGAS/KILO) /* (kJ/(mol K)) */
#define FARADAY (E_CHARGE*AVOGADRO) /* (C/mol) */
#define ELECTRONVOLT (E_CHARGE*AVOGADRO/KILO) /* (kJ/mol) */
#define PLANCK1 (6.6262e-34) /* J s */
#define PLANCK (6.6262e-34*AVOGADRO/(PICO*KILO)) /* (kJ/mol) ps */
#define EPSILON0 (5.72765E-4) /* (e^2 / Na (kJ nm))
== (e^2 mol/(kJ nm)) */
#define SPEED_OF_LIGHT (2.9979245800E05) /* nm/ps */
#define ATOMICMASS_keV (940000.0) /* Atomic mass in keV */
#define ELECTRONMASS_keV (512.0) /* Electron mas in keV */
/* Improved accuracy (PL & EL, 20090421) */
#define FACEL (332.0636930*CAL2JOULE)/* (10 * (ONE_4PI_EPS0)) */
#define ONE_4PI_EPS0 (FACEL*0.1) /* 1/(4*pi*e0)*/
#define PRESFAC (16.6054) /* bar / pressure unity */
#define ENM2DEBYE 48.0321 /* Convert electron nm *
* to debye */
#define DEBYE2ENM 0.02081941
/* to convert from a acceleration in (e V)/(amu nm) */
/* FIELDFAC is also Faraday's constant and E_CHARGE/(1e6 AMU) */
#define FIELDFAC (FARADAY/KILO)
/* to convert AU to MD units: */
#define HARTREE2KJ 4.3597482e-21
#define BOHR2NM 0.0529177249
#define HARTREE_BOHR2MD (HARTREE2KJ*AVOGADRO/BOHR2NM)
/* The four basic units */
#define unit_length "nm"
#define unit_time "ps"
#define unit_mass "u"
#define unit_energy "kJ/mol"
/* Temperature unit, T in this unit times BOLTZ give energy in unit_energy */
#define unit_temp_K "K"
/* Charge unit, electron charge, involves ONE_4PI_EPS0 */
#define unit_charge_e "e"
/* Pressure unit, pressure in basic units times PRESFAC gives this unit */
#define unit_pres_bar "bar"
/* Dipole unit, debye, conversion from the unit_charge_e involves ENM2DEBYE */
#define unit_dipole_D "D"
/* Derived units from basic units only */
#define unit_vel unit_length "/" unit_time
#define unit_volume unit_length "^3"
#define unit_invtime "1/" unit_time
/* Other derived units */
#define unit_surft_bar unit_pres_bar " " unit_length
/* SI units, conversion from basic units involves NANO, PICO and AMU */
#define unit_length_SI "m"
#define unit_time_SI "s"
#define unit_mass_SI "kg"
#define unit_density_SI unit_mass_SI "/" unit_length_SI "^3"
#define unit_invvisc_SI unit_length_SI " " unit_time_SI "/" unit_mass_SI
#ifdef __cplusplus
}
#endif
#endif /* _physics_h */
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