Inclusion of correlation structure glmer function of package lme4

Dear,

Good night.

I am using the glmer function of the lme4 package of R. My answer is
Bernoulli and my data are longitudinal.

In the bild Package, I have already found article using correlation
structures.

Is there any way I can use the glmer function and be able to include a
correlation structure? If it is not possible, could you tell me which
default is?

The code in R is only to facilitate the help.

## generalized linear mixed model
library(lme4)
(gm1 <- glmer(cbind(incidence, size - incidence) ~ period + (1 | herd),
              data = cbpp, family = binomial))

Thanks

Marcos Paulo