RSH is implemented as a separate functional (so far).
New variables alpha_RSH, beta_RSH and mu_RSH are added. There is
still duplicated code with HSEFunctional and PBEFunctional.
The InteractionPotential class is removed and ExchangeOperator is
modified to implement the interaction potential depending on the
parameters alpha_RSH, beta_RSH and mu_RSH.
Functionality needs testing for HF and all hybrid functionals.

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1926 cba15fb0-1239-40c8-b417-11db7ca47a34

The derivative of the enhancement factor Fx(s) in HSE had an incorrect slope
because a factor of s was missing. As a consequence the term 1/s Fx(s) was
not bounded for s -> 0.

Fix derivative of F(s) and H(s), which were lacking the factor s and s^2 respectively.

Rename FT to int_pot in ExchangeOperator.

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1406 cba15fb0-1239-40c8-b417-11db7ca47a34

Although G=0 is not divergent for HSE, the large changes near the
origin cause problems in the numerical calculation of the nonlocal
exchange energy. To correct this a "divergence" correction analogously
to PBE0 is introduced.

subtract exp(-rcut^2*G^2)*V(G) to make Fourier transform stable near G=0
set all energy contributions of G=0 in main loop to 0
add divergence correction at the end modifying the PBE0 one appropriately

new function in HSEFunctional is used to calculate the scaling of the
HSE "divergence" relative to the PBE0 one
InteractionPotential.h contains this additional function

the integrals ~k^2 are not evaluated because they are of higher order
(in PBE0 the potential is ~k^{-2} near G=0, so that the k^2 terms are
important, in HSE the potential is ~const. near G=0, so that the k^2
terms do not contribute a lot

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1404 cba15fb0-1239-40c8-b417-11db7ca47a34

for stress calculations not only the potential but the derivative is needed as well
create class that encapsulates potential and derivative
generator function in HSEFunctional to create the new type

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1400 cba15fb0-1239-40c8-b417-11db7ca47a34

in HSEFunctional define static function that evaluates FT of the erfc(wr)/r potential
screening omega must be static, so that this function can use it

bugfixes in local xc energy
use a instead of (1-a) [a = 1/4]
add ec += h line in nonmagnetic correlation energy

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1385 cba15fb0-1239-40c8-b417-11db7ca47a34

check that HSE enhancement factor and its derivatives agree between
FLEUR and the QBOX implementation

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1383 cba15fb0-1239-40c8-b417-11db7ca47a34

implement the setxc function and use the HSE exchange and PBE correlation functions
to calculate the appropriate xc energy and potential for the HSE functional

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1382 cba15fb0-1239-40c8-b417-11db7ca47a34

add spin-polarized correlation energy from PBE to HSE functional

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1381 cba15fb0-1239-40c8-b417-11db7ca47a34

add non-spin-polarized correlation energy calculation to HSE functional

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1380 cba15fb0-1239-40c8-b417-11db7ca47a34

write helper function that constructs the HSE enhancement factor and
combines it with the PBE functional to calculate the local exchange
energy and potential

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1379 cba15fb0-1239-40c8-b417-11db7ca47a34

apply correction to reduced gradient to satisfy Lieb-Oxford bound

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1378 cba15fb0-1239-40c8-b417-11db7ca47a34

combine the calculated integrals to the enhancement factor

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1377 cba15fb0-1239-40c8-b417-11db7ca47a34

calculate integrals of exchange hole

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1376 cba15fb0-1239-40c8-b417-11db7ca47a34

implement integral in the limit of large arguments

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1375 cba15fb0-1239-40c8-b417-11db7ca47a34

implement integration of first part of exchange hole
move exchange hole constants to global scope of the file, so that they
don't have to be defined in every function

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1374 cba15fb0-1239-40c8-b417-11db7ca47a34

transfer the G(s) function from the FLAPW implementation

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1372 cba15fb0-1239-40c8-b417-11db7ca47a34

transfer the function F(s) and H(s) from the FLAPW implementation in fleur

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1371 cba15fb0-1239-40c8-b417-11db7ca47a34

constructor checks consistency of array dimensions and allocates
the arrays use in the calculation of the exchange correlation energy
include dummy routine for setxc so that code compiles

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1370 cba15fb0-1239-40c8-b417-11db7ca47a34

create header similar to PBE functional

git-svn-id: http://qboxcode.org/svn/qb/branches/hse-dev@1369 cba15fb0-1239-40c8-b417-11db7ca47a34

git-svn-id: http://qboxcode.org/svn/qb/trunk@644 cba15fb0-1239-40c8-b417-11db7ca47a34

git-svn-id: http://qboxcode.org/svn/qb/trunk@638 cba15fb0-1239-40c8-b417-11db7ca47a34

git-svn-id: http://qboxcode.org/svn/qb/trunk@515 cba15fb0-1239-40c8-b417-11db7ca47a34

git-svn-id: http://qboxcode.org/svn/qb/trunk@414 cba15fb0-1239-40c8-b417-11db7ca47a34

git-svn-id: http://qboxcode.org/svn/qb/trunk@251 cba15fb0-1239-40c8-b417-11db7ca47a34

git-svn-id: http://qboxcode.org/svn/qb/trunk@123 cba15fb0-1239-40c8-b417-11db7ca47a34