/*******************/
/* mcp_constants.h */
/*******************/
#ifndef _MCP_CONSTANTS_H
#define _MCP_CONSTANTS_H

/** universal constants **/
#ifndef PI
#define PI (acos(-1.))
#endif
#define AVO   6.0221367E+23
#define BOLZ  1.380658E-23    /* in Joule */
#define HBAR  1.054589E-34    /* in Joule.s */

/** argon constants **/
#define ARGON_MASS  (39.948*1E-3/AVO) /* in kg */

/** argon LJ6-12 constants **/
#define SIGMA     3.405E-10     /* in meter */
#define EPSILON   (119.8*BOLZ)  /* in Joule */

/** reduced units based on argon LJ6-12 **/
#define UENERGY_IN_JOULE EPSILON
#define ULENGTH_IN_METER SIGMA
#define UMASS_IN_KG ARGON_MASS
/* from now on are all derived reduced units --> */
#define ULENGTH_IN_ANGSTROM (SIGMA*1E10)
#define UTIME_IN_SECOND \
sqrt(UMASS_IN_KG*ULENGTH_IN_METER*ULENGTH_IN_METER/UENERGY_IN_JOULE)
#define UTIME_IN_PS (UTIME_IN_SECOND/1.E-12) 
#define UFREQ_IN_HZ (1./UTIME_IN_SECOND/2./PI)
#define UFREQ_IN_THZ (1e-12*UFREQ_IN_HZ)   
#define EV_IN_JOULE 1.60217733E-19
#define UFREQ_IN_MEV (HBAR*2*PI*UFREQ_IN_HZ/EV_IN_JOULE*1000.)

/* Woon's ab initio pair potential */
#define HARTREE_IN_JOULE 4.3597482E-18
#define BOHR_RADIUS_IN_ANGSTROM 0.529177249
#define WOON_EPSILON (0.4228*HARTREE_IN_JOULE/1000./UENERGY_IN_JOULE)
#define WOON_RE (7.1714*BOHR_RADIUS_IN_ANGSTROM/ULENGTH_IN_ANGSTROM)
#define WOON_Q  0.6060
#define WOON_KE (0.6627*HARTREE_IN_JOULE/1000./UENERGY_IN_JOULE \
		 /BOHR_RADIUS_IN_ANGSTROM/BOHR_RADIUS_IN_ANGSTROM \
		 *ULENGTH_IN_ANGSTROM*ULENGTH_IN_ANGSTROM)
#define WOON_K1 sqrt((WOON_Q+1)*WOON_KE/WOON_Q/WOON_EPSILON)
#define WOON_K2 sqrt(WOON_Q*WOON_KE/(WOON_Q+1)/WOON_EPSILON)
/* D. E. Woon, Chem. Phys. Lett. 204, 29 (1993) */

/* potential cutoff in reduced length unit */
#define CUTOFF (2.5*3.39/ULENGTH_IN_ANGSTROM)
/* maximum possible reduced density of the solid */
#define MAXDENSITY 2.0
#define MAXNEIGHBOR ((int)(4./3.*PI*CUTOFF*CUTOFF*CUTOFF*MAXDENSITY))
    
/* program constants */
#define MAX_STRING_LENGTH 150

/* parallelization constants */    
#define MAX_SHM_SEG 6     /* on Xolas, otherwise EMFILE error */
#define MAX_PROCESSORS 8  /* on Xolas, otherwise EMFILE error */
#define ORDER_OF_INTEGRATION 12

/* commands for collective action */
#define U_TO_COPY      1
#define U2_TO_COPY     2
#define U4_TO_COPY     3
#define U6_TO_COPY     4
#define U8_TO_COPY     5
#define COPY_TO_U2    11
#define COPY_TO_U4    12
#define COPY_TO_U6    13
#define COPY_TO_U8    14
#define COPY_TO_U10   15
#define ZERO_U2_U10   21
#define SLAVE_DIE     99
    
#endif /* _MCP_CONSTANTS_H */