Calculate α and β in Probit Model in R

[newbalancer]

I am facing following issue: I want to calculate the α and β from the following probit model in R, which is defined as:

Probability = F(α + β sprdt ).

I can calculate probabilities for the entire dataset, the coeffcients etc. but I not know how to get the constant α and β.

The purpose is to determine the Spread in Excel that corresponds to a certain probability. E.g: Which Spread corresponds to 50% etc.

Thank you in advance!

[FJCC]

Sorry if I am off target here, aren't α and β the coefficients of the fit produced by the glm function?

FIT <- glm(Outcome ~ x, data = df, family = binomial(link = "probit"))
FIT$coefficients