JAMESS' FORTRAN90 standard syntax.

jamess_standard.f90

! Variable declaration:
! =========================
!
! 1) Pythonic naming is used. See: http://legacy.python.org/dev/peps/pep-0008/#naming-conventions
! 2) In brief, this means "lowercase" or "lower_case_with_underscores" are acceptable examples.
! 3) Use descriptive naming.
! 4) Use of abbreviations is discouraged, unless they are very standard. 
!     - E.g. "kcal" for kilocalories is acceptable.
!     - E.g "http" for hypertext transfer protocol is acceptable.
!     - E.g "disp_ver" instead of, say, dispersion version is not acceptable. 
!      For instance, does disp. mean display or dispersion? Nobody will know
! 5) Every variable has it's own line and description
! 6) Always use implicit none

! Good:

! Identifier for the version of dispersion correction used.
integer dispersion_version

! Bad:

! dispersion version
integer disp_ver

! I'll rip your balls off:
integer dispver

! OMG NO:
integer dver

! You are killing me:
INTEGER IDSPVER

! Constant values use the parameter tag.
! Constant values are in full caps in accordance with PEP8.
! In brief, this means "UPPERCASE" or "UPPER_CASE_WITH_UNDERSCORES" are acceptable examples.

! Convert eV (electron volts) to kJ (kilojoule)
double precision, parameter :: EV_TO_KJ = 1.6021773d-22





! IF-STATEMENTS:
! =========================

! Standard
if (do_gradient) then
  call do_scf(arg)
endif

! Acceptable version, strictly for one-liners.
if (do_gradient) call do_scf(arg)

! Don't do this
if (do_gradient)
  call do_scf(arg)
  
! Somebody might do this:
if (do_gradient)
  write (*,*) "Doing SCF now"
  call do_scf(arg) ! Now do_scf() is called even if do_gradient.eq..false.