from their
results on 
and 
using 
, obtaining 
and 
. Their results for 
, 
,
, and 
form a thermodynamically self-consistent set.
The value of 
can also be estimated by new theories and
experiments independent of the Braginsky and Roberts approach that
have arisen in the last four years. The value of 
at
300 K for fcc solid iron has been measured up to 40 GPa by Boehler
et al. [1990], whose data fall on a straight line in
versus 
space. This correlation shows that the law
[ Anderson, 1967] holds over the pressure range measured, and that
. For a high compression such
as found in the core, the above equation needs to be modified, since
is a function of 
(but not 
)
[ Anderson et al., 1992; Chopelas and Boehler, 1992].
This dependence requires a parameter, 
,
that is independent of T but varies linearly with
volume [ Anderson and Isaak, 1993].
The Anderson-Isaak equation for 
at high compression is
where 
.
Anderson et al. [1992] found that the isotherms of
this equation converge at high T, so there is no temperature
effect on 
at high compression.
Assuming that 
for liquid iron is the same
as found for fcc solid iron, taking 
,
which seems to be universally true for silicates,
and using 
for liquid iron at ambient
conditions [ Wood, 1993], I find 
.
This is close to 
at the ICB used by Braginsky
and Roberts 
.
From the discussion above, I find 
,
which is somewhat close to the value
of 
used by Braginsky and Roberts [1995],
.
For comparison, Ahrens and Duffy [1993] reported that
from shock wave measurements 
for
solid hcp Fe, and 
will
be a little less for 
.
Stacey [1994] estimated that 
at mid core
is 
,
which agrees well with the Braginsky and Roberts values.
Jeanloz and Wenk [1988] estimated
for the inner core.