The CASINO forum

Sorry, the time steps should have been 0.001 and 0.00025 a.u. (ratio of 4:1), with populations of 1024 and 4096, respectively (4:1), for optimal efficiency (with twice as many statistics accumulation steps for the smaller time step). The shortest length scale in an all-electron calculation is the Bo...

Dear Vladimir, [b]All-electron DMC calculations with different Jastrow factors ought to agree exactly (within statistical error bars) in the limit of zero time step, infinite population and with an adequate equilibration period...[/b] For an aluminium atom (Z=13) the Bohr radius is 1/13 a.u., sugges...

Dear Sharma, It's inevitable, and is not a problem. If you were to perform repeated VMC calculations with exactly the same wave function then the VMC energies would bounce about by an amount given by the statistical error bars on the VMC energy. If you also perform a stochastic optimisation of the p...

Sorry, I've no idea what the problem is.

Best wishes,

Neil.

Dear Vinod, What happens if you take the example submit.cmd script and replace "pi_mpi" with "casino", then copy the CASINO binary from ~/CASINO/bin_qmc/$CASINO_ARCH/opt/casino into the working directory and submit the job? I can't help much with making a working job-submission s...

Dear Rajesh, I would always trust energy minimisation rather than variance minimisation when optimising a parameter (such as Rex) that affects the nodal surface of the trial wave function. Your emin calculation looks OK to me. The energies are bouncing about by rather more than the statistical error...

Dear Vinod, Could you ask the computer centre to provide you with a sample job-submission script for submitting a job to execute the CASINO binary, which can be found in CASINO/bin_qmc/$CASINO_ARCH/opt/casino on a given number of cores? Once you have a working job-submission script, it will be easie...

Dear Rajesh, I've attached modified input files for the example you sent. The main changes I made are: (i) I defined a custom spin-dependence (see the block at the end of input) and used it in the U term; (ii) I added a plane-wave two-body p term to the Jastrow; (iii) I removed the QCUSP term from t...

Dear Rajesh, Note that you are using the same two-body terms between pairs of electrons and between electrons and holes. Since the electrons and holes have the same mass, it would be best to define a custom spin dependence with the pair groupings (1-1,2-2) and (1-2). Alternatively you could set the ...

Dear Rajesh, I am running your example on four cores with the same random seed as you... I've got to 69 cycles so far without problems (see attached out file). If you diff the out file with yours you will see that the first VMC calculation is exactly the same. After that differences creep in, becaus...