[R] fix variance parameter values for lmer estimation

Dear list-members, a model is fit with lmer, but I want to force the variance parameter values to be as defined by me I thought, use 'start' to specify initial values and only allow for one iteration ? my question is how to do that ? to specify the 2x2 matrix of variance parameter values:

[R] set initial parameter values for GLMM estimation

Dear list members, I look for a way (or alternative) to specify initial values when estimating linear mixed models in R, and to avoid iterative estimation. This is a way to control specific parameter values (eg. variance parameter values) such that the result (F-value) is based on them. This