Background evolution in quintessence module

Use of Cobaya. camb, CLASS, cosmomc, compilers, etc.
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Chudaikin Anton
Posts: 6
Joined: April 26 2013
Affiliation: inr

Background evolution in quintessence module

Post by Chudaikin Anton » February 17 2014

I want to make f(R) Starobinsky's truly background evolution in CAMB using quintessence module. In Einstein metric potential energy equils

[tex]V(\psi)=\frac{\lambda R_{s}}{2\kappa^2}e^{-\frac{4\kappa^{2}\psi}{\sqrt{6}}}(1-(2n+1)\Big(-\frac{\kappa^{2}\psi}{\sqrt{6}n\lambda}\Big)^{\frac{2n}{2n+1}})[/tex]

In code I print using [tex]phi=\kappa^2\psi[/tex]:

Vofphi=(lambda*Rs/(2*norm2))*exp(-4*phi/sqrt(6.))*(1-(2*n+1)* (-phi/(sqrt(6.)*n*lambda))**(2*n/(2*n+1)))

where

norm2=(Tpl/(Mpc/c))**2 - convert \kappa^2 to units of Mpc^2
Rs - calculated in units of 1/Mpc^2
=>Vofphi - calculated in units of 1/Mpc^4

In code:
Tpl=5.391d-44*root8pi !Tpl = sqrt(8 pi G hbar/c^5)
MPC_in_sec = Mpc/c ! Mpc/c = 1.029272d14 in SI units

After running the programme I see

Error in dverk, x = 2812.0000000000000 xend= 2811.0000000000000

What is the problem? Additionally, I don't understand the sence of norm constant in the code (stated norm= 1d-122).

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