Use the "new" (?) xcontrol

[pierre-24]

Describe the bug
I can imagine some of the reason that lead to the separation of xtb and xtb4stda, but it seems that the later still use the "old" input file format (and thus rely to command lines options for charge, solvent ...), while xtb allow to provide the additional informations in the input file ($chrg, $gbsa), which I find way more easier (for example, to automatically convert from output of other program, then running xtb4stda without having to know what the charge is).

Again, I guess that the reason this is not done yet (among other things like "not enough time") is that xcontrol provides a lot more options that only what is required here (which seems like a tuned single point), but that would definitely ease the life of the end user.

You could even imagine making the xcontrol part an external library shared between the two projects.

To Reproduce

Running xtb4stda on a file with $chrg 1 in it does not gives an error, but the charge is not considered (and thus the molecule is considered open-shell).

Expected behaviour
Charge (and other information) are considered.

Additional context
None.

[awvwgk]

There is an input format called set block here, which allows something like

$set
   charge 1
   uhf 2
$end

when append to a xyz or Turbomole coordinate file. The implementation is here:

xtb4stda/src/molbld.f

Lines 344 to 354 in f892525

	if(index(line,'chrg ').ne.0.or.
	. index(line,'charge ').ne.0)then
	call readl(line,xx,nn)
	ichrg=int(xx(1))
	chrg =ichrg
	endif
	if(index(line,'uhf ').ne.0)then
	call readl(line,xx,nn)
	nalphabeta=int(xx(1))
	spin =nalphabeta
	endif

Considering the detailed input in xtb version 6, one might guess it evolved as replacement of the set block input format. But there are no plans for back ports from version 6 to this version 5 remnant.

[pierre-24]

At least there is an input section to set some of those variables, which is what I wanted to know :)