import numpy as np
import math
from scipy import optimize
c = 3e10
G = 6.67428e-8
Msun = 1.989e33
dyncm2_to_MeVfm3 = 1./(1.6022e33)
gcm3_to_MeVfm3 = 1./(1.7827e12)
oneoverfm_MeV = 197.33
m_e = 2.5896 * 10**-3
m_mu = 0.53544
m_n = 4.7583690772
m_p = 4.7583690772
J_B = 1/2.
b_B = 1
m_l = [m_e, m_mu]
m_b = [m_p, m_n]
Matrix_b = np.array([[1., 1., 1/2., 1., 1., 1.],[1., 0., -1/2., 1., 1., 1.]])
Matrix_l = np.array([[0., -1., 1/2.],[0., -1., 1/2.]])
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def initial_values(rho, theta):
"""Outputs the the sigma, omega, rho term and chemical potential of electron and neutron at
given initial density
Args:
rho (float): given nuclear density
theta (array): paramters of determine a RMF model in lagrangian, here we have 10 parameters.
Returns:
sigma (float): sigma term in lagrangian
omega (float): omega term in lagrangian
rho_03 (float): rho term in lagrangian
mu_n (float): chemical potential of neutron matter
mu_e (float): chemical potential of electron portion
"""
m_sig, m_w, m_rho, g_sigma, g_omega, g_rho, kappa, lambda_0, zeta, Lambda_w = theta
m_e = 2.5896 * 10**-3
m_mu = 0.53544
m_n = 4.7583690772
m_p = 4.7583690772
rho_0 = 0.1505
sigma = g_sigma*rho/(m_sig**2)
rho_03 = -g_rho*rho/(2.*(m_rho**2))
omega = rho*((((m_w**2)/g_omega)+\
(2.*Lambda_w*((g_rho*rho_03)**2)*g_omega))**(-1.))
m_eff = m_n-(g_sigma*sigma)
mu_n = m_eff + g_omega*omega + g_rho*rho_03*Matrix_b[1, 2]
mu_e = 0.12*m_e*(rho/rho_0)**(2/3.)
return sigma, omega, rho_03, mu_n, mu_e
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def functie(x, args):
"""iterate the the sigma, omega, rho term and chemical potential of electron and neutron at
any given density
Args:
x (array): initial sigma omega rho and chemical potential from initial_values function
args (array): paramters of determine a RMF model in lagrangian, here we have 10 parameters.
Returns:
sigma (float): sigma term in lagrangian
omega (float): omega term in lagrangian
rho_03 (float): rho term in lagrangian
mu_n (float): chemical potential of neutron matter
mu_e (float): chemical potential of electron portion
"""
m_sig = args[0]
m_w = args[1]
m_rho = args[2]
g_sigma = args[3]
g_omega = args[4]
g_rho = args[5]
kappa = args[6]
lambda_0 = args[7]
zeta = args[8]
Lambda_w = args[9]
rho = args[10]
m_e = 2.5896 * 10**-3
m_mu = 0.53544
m_n = 4.7583690772
m_p = 4.7583690772
J_B = 1/2.
b_B = 1
m_l = np.array([m_e, m_mu])
m_b = np.array([m_p, m_n])
Matrix_b = np.array([[1., 1., 1/2., 1., 1., 1.],[1., 0., -1/2., 1., 1., 1.]])
Matrix_l = np.array([[0., -1., 1/2.],[0., -1., 1/2.]])
sigma = x[0]
omega=x[1]
rho_03 = x[2]
mu_n = x[3]
mu_e = x[4]
rho_B_list = []
rho_SB_list = []
q_list = []
m_eff = m_n - (g_sigma*sigma)
#i = 0
#j = 0
for i in range(len(Matrix_b)):
#while i < len(Matrix_b):
mu_b = Matrix_b[i,0]*mu_n - Matrix_b[i, 1]*mu_e
E_fb = mu_b - g_omega*omega - g_rho*rho_03*Matrix_b[i,2]
k_fb_sq = E_fb**2 - m_eff**2
if k_fb_sq < 0:
k_fb_sq = np.clip(k_fb_sq, a_min=0.0, a_max=None)
E_fb = m_eff
k_fb = math.sqrt(k_fb_sq)
rho_B = ((2*J_B) + 1)*b_B*k_fb**3 / (6.*math.pi**2)
rho_SB = (m_eff/(2.*math.pi**2))*(E_fb*k_fb - \
(m_eff**(2))*np.log((E_fb + k_fb)/m_eff))
rho_B_list.append(rho_B)
rho_SB_list.append(rho_SB)
Q_B = ((2.*J_B) + 1.)*Matrix_b[i,1]*k_fb**3 / (6.*math.pi**2)
q_list.append(Q_B)
#i += 1
for j in range(len(Matrix_l)):
#while j < len(Matrix_l):
mu_l = Matrix_l[j,0]*mu_n - Matrix_l[i,1]*mu_e
E_fl = mu_l
k_fl_sq = E_fl**2 - m_l[j]**2
k_fl_sq = np.clip(k_fl_sq, a_min = 0.0, a_max = None)
k_fl = math.sqrt(k_fl_sq)
Q_L = ((2.*J_B) + 1.)*Matrix_l[i,1]*(k_fl**3) / (6.*(math.pi**2))
q_list.append(Q_L)
#rho_l = k_fl**3 / (3.*(math.pi**2))
#rho_list.append(rho_l)
f = [(sigma*(m_sig**2)/g_sigma - sum(np.array(rho_SB_list)*Matrix_b[:,3])
+(kappa*(g_sigma*sigma)**2)/2. + (lambda_0*(g_sigma*sigma)**3)/6.)**2,
(omega*(m_w**2)/g_omega - sum(np.array(rho_B_list)*Matrix_b[:,4]) + (zeta*(g_omega*omega)**3)/6.\
+2.*Lambda_w*g_omega*omega*(rho_03*g_rho)**2)**2,
(rho_03*(m_rho**2)/g_rho - sum(np.array(rho_B_list)*Matrix_b[:,5]*Matrix_b[:,2])+2.*Lambda_w*g_rho*rho_03*(omega*g_omega)**2)**2,
(rho - sum(rho_B_list))**2,
(sum(q_list))**2]
return f
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def Energy_density_Pressure(x, rho, theta):
"""Generate pressure and energy density two EOS ingredient from given RMF term and given parameters,
Args:
x (array): An array that consists of the initial values of sigma, omega, rho, and chemical
potential obtained from the initial_values function.
rho (float): The central density from which the computation of the equation of state begins.
theta (array): An array representing the parameters used to determine a RMF model in the
Lagrangian. In this case, the RMF model is defined by 10 parameters.
Returns:
energy_density (float): EOS ingredient, energy density in g/cm3
pressure (float): EOS ingredient, pressure in dyn/cm3
"""
sigma, omega, rho_03, mu_n, mu_e = x
m_sig, m_w, m_rho, g_sigma, g_omega, g_rho, kappa, lambda_0, zeta, Lambda_w = theta
m_e = 2.5896 * 10**-3
m_mu = 0.53544
m_n = 4.7583690772
m_p = 4.7583690772
J_B = 1/2.
b_B = 1
m_l = np.array([m_e, m_mu])
m_b = np.array([m_p, m_n])
energy_b = 0
energy_l = 0
multi = 0
m_eff = m_n - (g_sigma*sigma)
for i in range(len(Matrix_b)):
mu_b = Matrix_b[i,0]*mu_n - Matrix_b[i, 1]*mu_e
E_fb = mu_b - g_omega*omega - g_rho*rho_03*Matrix_b[i,2]
k_fb_sq = E_fb**2 - m_eff**2
if k_fb_sq < 0:
k_fb_sq = 0.0
E_fb = m_eff
k_fb = math.sqrt(k_fb_sq)
rho_B = ((2.*J_B) + 1.)*b_B*(k_fb**3) / (6.*math.pi**2)
multi = multi + mu_b*rho_B
energy_baryon = (1/(8.*(math.pi**2)))*(k_fb*(E_fb**3)\
+ (k_fb**3)*E_fb - np.log((k_fb + E_fb)/m_eff)*m_eff**4)
energy_b = energy_b + energy_baryon
for j in range(len(Matrix_l)):
mu_l = Matrix_l[i, 0]*mu_n - Matrix_l[j, 1]*mu_e
k_fl_sq = mu_l**2 - m_l[j]**2
if k_fl_sq < 0.0:
k_fl_sq = 0.0
k_fl = math.sqrt(k_fl_sq)
rho_l = k_fl**3 / (3.*math.pi**2)
multi = multi + mu_l*rho_l
energy_lepton = (1/(8.*(math.pi**2)))*(k_fl*(mu_l**3)\
+mu_l*(k_fl**3)-(m_l[j]**4)*np.log((k_fl+mu_l)/m_l[j]))
energy_l = energy_l + energy_lepton
sigma_terms = 0.5*((sigma*m_sig)**2) + (kappa*((g_sigma*sigma)**3))/6.\
+ (lambda_0*((g_sigma*sigma)**4))/24.
omega_terms = 0.5*((omega*m_w)**2) +(zeta*((g_omega*omega)**4))/8.
rho_terms = 0.5*((rho_03*m_rho)**2)+ + 3.*Lambda_w*((g_rho*rho_03*g_omega*omega)**2)
energy_density = energy_b + energy_l + sigma_terms \
+ omega_terms + rho_terms
Pressure = multi - energy_density
return energy_density, Pressure
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def compute_EOS(eps_crust, pres_crust, theta):
"""Generate core part equation of state, main function, from RMF model,
Args:
eps_crust (array): the energy density of crust EoS in MeV/fm3, times a G/c**2 factor
pres_crust (array): the pressure from crust EoS model in MeV/fm3, times a G/c**4 factor
theta (array): An array representing the parameters used to determine a RMF model in the
Lagrangian. In this case, the RMF model is defined by 10 parameters.
Returns:
energy_density (float): EOS ingredient, energy density in g/cm3
pressure (float): EOS ingredient, pressure in dyn/cm3
"""
dt = 0.05
rho_0 = 0.1505
x_init = np.array(initial_values(0.1*rho_0, theta))
Energy = []
Pressure = []
for i in range(1, 125):
rho = i*dt*rho_0
arg = np.append(theta, rho)
sol = optimize.root(functie, x_init ,method='lm',args = arg)
Re= Energy_density_Pressure(x_init, rho,theta)
Energy.append(Re[0]*oneoverfm_MeV/gcm3_to_MeVfm3)
Pressure.append(Re[1]*oneoverfm_MeV/dyncm2_to_MeVfm3)
x_init = sol.x
Energy = np.array(Energy)
Pressure = np.array(Pressure)
end = 0
for i in range(0,len(Energy)-1):
if Energy[i]*G/c**2 > max(eps_crust) and i >18:
end = i+2
break
end += 1
ep = Energy[end::] * G/c**2
pr = Pressure[end::] * G/c**4
return ep, pr