I am a new user in QMC and I use this program for a little time, for this reason I don't have much experience.

This last week I tried to obtain a dissociation energy with the casino program. First, I optimized the Jastrow parameters and then I calculated the DMC energy. To obtain the energy I used 100000 dmc steps and 2000 configurations for the statistics and I repeated this for different time step(0.001, 0.0025 and 0.005). The problem is when the time step is small(0.001) I represent the reblock graph for the dmc and I don't find the "plateau" at small values of dtdmc in the reblock.

Block len Std error Err in error

1 1.190778E-04 2.663150E-07

2 1.579759E-04 4.996579E-07

4 2.119098E-04 9.478781E-07

8 2.847128E-04 1.801075E-06

16 3.808577E-04 3.407375E-06

32 5.042606E-04 6.380601E-06

64 6.531861E-04 1.168938E-05

128 8.417852E-04 2.131036E-05

256 1.056928E-03 3.785678E-05

512 1.269994E-03 6.439546E-05

1024 1.481055E-03 1.064076E-04

2048 1.718183E-03 1.754235E-04

4096 1.815489E-03 2.638888E-04 *** BEST ***

8192 1.489433E-03 3.122125E-04

16384 1.728491E-03 5.359214E-04

32768 1.592540E-03 7.764297E-04

Then I try to increment the number of steps (600000) but I found a value very similar.

When I increase the value of dtdmc(0.0025 and 0.005) a "plateau" appear at high values(Blocklen=4096) even if I increase the number of steps to 800000. For this reason I want to know which value of dtdmc I have to use, because I don't know how to choose the right value. Should I increase more the number of steps to obtain a better reblock or I use the lowest value of dtdmc in which appear the "plateau"?.