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/// \file
/// Contains constants for unit conversions.
///
/// The units for this code are:
/// - Time in femtoseconds (fs)
/// - Length in Angstroms (Angs)
/// - Energy in electron Volts (eV)
/// - Mass read in as Atomic Mass Units (amu) and then converted for
/// consistency (energy*time^2/length^2)
/// Values are taken from NIST, http://physics.nist.gov/cuu/Constants/
#ifndef _CONSTANTS_H_
#define _CONSTANTS_H_
/// 1 amu in kilograms
#define amuInKilograms 1.660538921e-27
/// 1 fs in seconds
#define fsInSeconds 1.0e-15
/// 1 Ang in meters
#define AngsInMeters 1.0e-10
/// 1 eV in Joules
#define eVInJoules 1.602176565e-19
/// Internal mass units are eV * fs^2 / Ang^2
static const double amuToInternalMass =
amuInKilograms * AngsInMeters * AngsInMeters
/ (fsInSeconds * fsInSeconds * eVInJoules);
/// Boltmann constant in eV's
static const double kB_eV = 8.6173324e-5; // eV/K
/// Hartrees to eVs
static const double hartreeToEv = 27.21138505;
/// Bohrs to Angstroms
static const double bohrToAngs = 0.52917721092;
#endif
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